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the corneous plate formed by the coalescence of the posterior lateral elements (epimera) is very narrow; and in other cases (Baris, &c.) the posterior part of the prosternum is thickened and overlies the suture on the median line, but without coming into contact with the mesosternum.

4th. The ventral segments never exceed five in number, and the first and second are usually larger and more closely connected, frequently even connate, with partially obliterated suture; the fifth is sometimes longer than the fourth, sometimes about equal to it.

5th. When there is any appreciable difference between the sexes, it is usually manifested by a greater elongation of the beak of the, indicating its use as an accessory organ of generation, for making the perforation in which the egg is subsequently placed by the soft ovipositor, and pushed down by the beak.

6th. The other sexual difference is in the addition of a small dorsal (or anal segment to the ; this character is, however, not obvious in several families, the morphological representative of this anal segment being completely retracted and covered by the pygidium. In others this segment is visible only from beneath, simulating, therefore, a sixth ventral.

7th. The very rare occurrence of articulated movable spurs at the end of the tibiæ; it is seldom, indeed, that more than one fixed mucro occurs, and in the species in which the tarsi are inserted laterally near the tip, this mucro becomes frequently elongated and curved; the outer angle of the tip is in these instances quite often prolonged into a curved digitation, like the terminal tooth of the front tibiæ of some Scaritini, of the family Carabida

8th. The head is most frequently prolonged in front of the eyes, forming a beak, which is usually narrower than the front, and frequently very slender. A flattened prolongation, similar to a beak, occurs in some genera of Cucujidæ, Pythida and demeride, but not elsewhere in the normal Coleoptera.

9th. In the vast majority of species the labrum is wanting; in some Scolytida it is feebly developed, but is present in normal form only in Rhinomaceride and Anthribida.

10th. Except in Rhinomacerida and Anthribida the palpi are short and rigid, with the joints diminishing in size; in those families they are slender and flexible, as in normal Coleoptera.

11th. In those genera in which the hind tibiæ are truncate and margined at tip, forming a surface called a corbel, this surface may be glabrous or scaly. In normal Coleoptera they are always glabrous, and in Hypocephalus alone they are densely clothed with hair.*

12th. A peculiar ridge on the inner surface of the elytra, into which the ascending margin of the metathoracic epimera and ventral segments fit, giving great firmness and solidity to the hinder part of the body. This

* LeConte, Trans. Am. Ent. Soc. v, 209.

ridge is rarely wanting; and is represented among normal Coleoptera, so far as I have examined, only in certain Buprestida.

These characters taken collectively, in addition to the two fundamental defining characters first mentioned, indicate a profound difference in organization, which isolates the Rhynchophora from all other Coleoptera. From this isolation results the necessity of classifying them upon other characters than those which are found useful in defining series and families in the normal Coleoptera. The great resemblance in general appearance of the insects of this type, and the endeavor to consider them as only a family in the whole series of Coleoptera, has caused the characters used in this memoir to be either undervalued or overlooked. I believe, however, that when attention is directed to them, and to certain other characters, 'which I have not had time to fully investigate, the arrangement of these insects into natural groups will be found as simple and intelligible as that of the normal Coleoptera.

Among the investigations which yet remain imperfect, I would mention as specially deserving of attention, the stridulating organs. There are in some genera spaces on the inner surface of the elytra, which have a pearly lustre, and which are probably capable, by friction against the ascending margin of the ventral segments, of producing a sound. I have mentioned these under the genus Listronotus, of the Phytonomini, but they are present in many genera of other tribes, and in fact, the Conotracheli and many others are known to emit a squeaking sound.

The homologies of the parts of the head, by reason of which the front portion becomes extended into a beak, and the basal piece on the under surface (which separates the gular sutures in normal Coleoptera) disappears, are also worthy of attention; so too are the larva, with the view of discovering some general characters in which they differ from those of other Coleoptera.

A more careful study should also be made of the antennæ of the Scolytide, by specimens mounted in Canada balsam, so that the homologies of the joints of the funicle, when they disappear may be ascertained. The subject, as treated in this memoir, is, I may say, barely sketched, and will yield to others, who may devote labor to it, not only the correction of errors I have made, but many new truths and generalizations greater in value than those to which I have attained.

The affinities of the families of Rhynchophora among themselves, and their resemblances to various series or families of the normal Coleoptera remain to be indicated.

The typical Rhynchophora, Curculionida, while exhibiting in the dif ferent tribes characters which are more individualized and combined with special structures in the other families, occupy a central position around which the latter may be grouped.

The Rhinomacerida, by the presence of a labrum and flexible palpi, as well as by the general form of body, and 11-jointed, non geniculate antennæ, indicate a resemblance to Rhinosimus, &c., of the Pythide. The Otiorhynchida, in the tribes with large mentum, and the Brachycerida show

strong analogy with the higher Tenebrionidæ, in which the buccal ca vi is entirely closed by the mentum.

By the gradual obsolescence of the deciduous mandibular appendage, al the scar, which is its natural consequent, the Otiorhynchida pass almost i sensibly into the Curculionida. The last named family through the Ei rhinini is affiliated with the Rhynchitidæ, and through the Barini with t] Calandrida and Cossonida.

The Hylastes group of the Scolytida shows strong affinities with the Co sonidir, and a slight reversion towards the Cryptorhynchini of the Cure lionido.

The Brenthida are isolated, and indicate a relationship which is neith of affinity or analogy, but rather of contemporaneous origin with Hypocep, alidæ, Rhysodidæ, Cupesidæ, and perhaps some other families of norma Coleoptera, which have been yet imperfectly studied. Nevertheless, b certain abnormal genera, not occurring in our fauna, they exhibit a r semblance in some characters to the sub-family Platypodide of the Scol! tidæ, and connect both, by their resemblances with the Colydiidæ of th Clavicorn series of normal Coleoptera.*

Some of the Scolytida in form and general appearance resemble the feeble groups (Choragus, &c.) of the Anthribidæ, but the characters of the latte are so peculiar, that they must be viewed as a synthetic type, combinin resemblances to very diverse series. The form of the mentum, if I hav interpreted it correctly, is found only in the Adephaga ( Amphizoa), whil the great sexual differences in the length of the antennæ occur only in th Cerambycide. The well developed labrum, filiform flexible palpi, straight 11-jointed antennæ, and epipleuræ indicate a higher organization than i found in other Rhynchophora. The complete consolidation, without su tures, of the elements of the under surface of the head and prothorax, indi cate a progress along the line of true Rhynchophorous development, upor which I have based the two fundamental defining characters. The pro gress in this instance has been carried so far as to cause the disappear ance of these very characters. If any resemblance to the normal Coleop tera could be seen to replace them, the Anthribida would be removed, a has been done with the Bruchida, to some other part of the system. Bu this is not the case, and they must remain, therefore, as the expression o the most perfect development thus far attained in the Rhynchophorous type.t

The classification here adopted is simply that set forth by me in the memoirf above cited, which was read before the National Academy of Sciences, at the session held at Washington, April, 1874; I have, however, left out the families Brachyceridæ, Amycterido and Belidæ, defined in that essay, but which are not represented in our fauna.

* It will be here remembered that Nematidium has the median suture behind the point of the prosternum precisely as in Rhynchophora.

† In this connection it is important to remark, that while the food of the Rhynchophora is almost universally vegetable tissues, either living or dead, Brachytarsus is a parasite upon a Hemipteron, of the genus Coetus, as narrated by Værdlinger, Stettin Ent. Zeitung, 1818, p. 230; Lacord., Gen. Col. vii, 181,

| American Naturalist, July, 1874.

1

There are three series, composed of eleven families, represented in Temperate and Arctic North America, which may be diagnosed as follows:

1. Abdomen ? $ alike ; pygidium small, elytra without lateral fold on inner surface...

HAPLOGASTRA. Labrum distinct, mandibles flat, simple...

Rhinomaceridæ. Labrum wanting : Mandibles flat, toothed on outer and inner edge Rhynchitidæ. stout, pincer-shaped......

Attelabidæ. II. Abdomen dissimilar ; o with an additional anal segment; pygid.

ium large ; elytra with acute lateral fold on in-
ner surface......

ALLOGASTRA.
A. Antenne with annulated or solid club.
Tarsi narrow, setose.
Gular margin prominent, prosternum exca-
vated....

Byrsopidæ.
Tarsi dilated, usually with a brush of hair beneath.

Mandibles with deciduous tip, leaving a scar Otiorhynchidæ.
Mandibles without scar, usually pincer-
shaped....

Curculionidæ. B. Antennæ with ten or eleven distinct joints..... Brenthidæ. III. Abdomen alike ; elytra with a distinct lateral fold on the inner surface...

..HETEROGASTRA.
A. Pygidium vertical or declivous :
Antennæ geniculate, clubbed ; labrum want-

ing ; last spiracle covered by ventral seg.
ments

Calandridæ.
Antennæ straight; labrum distinct ; last spir-

acle not covered by ventral segments ; py-
gidium deeply notched to receive sutural
apex of elytra......

Anthribidæ.
B. Pygidium horizontal, smaller :
Antennæ geniculate, clubbed ; terminal edge

of last ventral segment acute, surrounding
the last dorsal; tibiæ generally compressed
and serrate.......

Scolytidæ.
Antenna straight, with annulated club ; max-

illæ very large, palpi and ligula feeble..... Apionidae Among the genera and species described in the present memoir, there will doubtless be many which, with more extended comparisons, will be found identical with those which occur in other regions. It will be a just

:

criticism, that I have failed to identify them with those already in the book In explanation of this, I would say that I have defined the tribes, gener and species, in many instances, by characters, which have been unnotice or neglected by previous investigators; and finding that quite frequently species, having a strong external resemblance, differed by structural charac ters of great moment, I did not feel warranted in applying to them name given to species, which agreed with them in the outline, vestiture and sculpture of the larger parts of the body, but which have been described from other zoological districts. It will be easy, by the aid of the structura characters which I have given, to identify my species with the types existing in European cabinets. I would rather that those I have named would sink into synonymy, than that, in the present condition of science, I should appear to teach false ideas regarding geographical distribution, which, when carefully studied, must give us important aid in attaining a knowledge of the causes and development of the existing order of things.

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