PHALACRIDZ. 245 
unattractive and little varied insects, they are neglected by collectors. Not a single 
species has previously been recorded as found in Central America, and only two or three 
are known from South America: so that nothing can be said at present as to the geogra- 
phical distribution of our genera and species. 
The Phalacride are very difficult insects to describe, owing to their remarkable want 
of variety of form, and to the very slight sculpture of the upper surface. In order to 
distinguish the species we must therefore fall back on the minor structural characters. 
The genera hitherto recognized are only five in number *: four of the five occur in our 
region, and I have been compelled to add five others, based entirely on the structure 
of the central pieces of the sternum and the form of the hind tarsi. This latter character 
calls for a few explanatory remarks. 
The tarsi are described by authors as five-jointed, but the fourth joint is so small, or so 
closely connected with the fifth, that it can rarely be detected; in Phalacrus and 
Tolyphus, indeed, the tarsi are not only practically tetramerous, but differ little in 
structure and clothing from the tetramerous tarsi seen in Hrotylide and in Phyto- 
phagous Coleoptera generally. On the other hand, in some of our Central-American 
species the hind tarsi are found to be greatly modified, the metatarsus being very much 
elongated, laterally compressed, and the clothing of the under surface absent. On 
comparing these forms with elongate metatarsus together, it is seen that though at first 
sight similar, they exhibit really two quite distinct modifications—in one of them 
(Litochrus) the elongation of the metatarsus is due to the basal joint having become 
very elongate; but in the other the first joint remains quite short, or is so completely 
soldered to the base of the second joint that it can scarcely be detected, and in this case 
the tarsus presents the appearance of being composed of a very elongate metatarsus or 
basal joint, then a small joint, followed by a moderately long terminal or claw-joint. 
The genera Hulitrus and Litolibrus are those in which this pseudo-trimerous structure 
of the hind tarsi is best exhibited. The modification of the hind foot in this direction 
seems specially characteristic of our Central-American Phalacride, and several species 
that I have placed in Olibrus and Husti/bus exhibit it to a greater or less extent, and 
will probably be ultimately separated from the forms of those genera found in Europe 
and North America. 
The structure of the pieces of the breast between the front and middle cox exhibits 
a similar series of modifications, but this modification does not go on part passw with 
that of the hind tarsus. In Hulitrus, the most interesting of the Central-American 
genera, and one which has a highly modified tarsus, the modification of the middle of 
the metasternum is extreme; but in Litolibrus, which has the tarsus nearly as much 
modified as Eulitrus, the breast is but little developed. 
With these explanations the genera I have proposed will, I think, be better under- 
* Augasmus, Motsch., is another genus, but the characters given are too indefinite to allow it to be more 
than guessed at. 
