TRICHOPTERYX. 133 
the elytra, with their extremity alone visible beyond the metasternum. Venter composed of six segments— 
1-5 nearly equal to each other in length, 6 rather longer, generally with a circularly curved deeply 
impressed line near the apex in the male sex. Legs generally robust, with the posterior coxe broadly 
laminated ; tibie armed with strong spurs, often dilated in the males ; tarsi 3-jointed, with the two basal 
joints generally very small, but sometimes strongly dilated in the males. 
With reference to the foregoing description of the labial palpi, I would observe that, 
as in other coleopterous families these organs possess only three articulations, it is 
scarcely probable that they should exceed that number in the Trichopterygide. Never- 
theless, throughout the whole of that family, the labial palpi conspicuously exhibit the 
appearance of a fourth joint at their base; which, if not a true articulation, must be 
an elevated portion of the anterior margin of the labium, and as such I have here and 
shall hereafter describe it. 
The species of Trichopteryx present a great variety of form, especially in the shape 
of the thorax; but their facial resemblance is so strongly marked, that they can easily 
be separated from all other genera. The chief difficulty lies in finding characters 
available for tabulation; the thorax affords the most obvious difference, but even there 
the gradations between the two extremes are so minute that it is sometimes difficult 
to determine to which section a species properly belongs. For this reason the characters 
given in the following Table must not be too strictly interpreted; but they will in a 
general manner assist in determining a species, and this is the utmost I can hope to 
accomplish. | 
This genus contains a very large number of species, and appears to be universally 
distributed. 
Table of the Central-American species known to me. 
Thorax wider, or much wider, than the elytra. 
Thorax widest at the base. 
Head and thorax black, the elytra castaneous. 
Form much attenuated posteriorly, with the thorax much dilated . rufescens. 
Form oblong, the thorax moderately dilated . . . . . . . . sémilior. 
Head, thorax, and elytra castaneous. 
Size larger, the surface very shining. . . . . . . . . . . (uetda. 
Size small, the surface finely and closely punctured. . . . . . crotch. 
Entirely fuscous. 
Surface clothed with grey pubescence . . . . . +. + + « « glauca. 
Surface clothed with fulvous pubescence . . . . . + . . ~ «atomaria. 
Entirely black, or fuscous-black. 
Form exceedingly convex. 
Size very large, without erect sete. . . . - - + «© + «+ godmani. 
Size moderate, with erect sete. 
Thorax deeply sculptured . . . . «© «© « « «© « . aalliberti. 
Thorax very lightly sculptured . . . . 1 « - + «grossa. 
