110 HETEROMERA. 
characteristic of this family, it being really present in the males of some, e. g. Nacerdes 
and Xanthochroa. No genus is known to me from Central America, except the intro- 
duced Nacerdes, with a single spur to the front tibie. With some few exceptions, 
the different species are apparently confined to a limited area, those frequenting the 
sea-shore being rather more widely distributed. ‘The numerous representatives from 
the Antilles, though closely allied in some cases, appear to be specifically different 
from those from the mainland of America. Many of the Central-American forms 
superficially resemble species of Telephoride. A considerable number of species 
frequent the sea-shore in all parts of the World. | 
We are much indebted to Dr. Horn for his assistance in communicating specimens 
of many of the North-American species of this family ; and examples of all the North- 
American genera and very many of the species have been examined; of the latter a few 
are common to the Southern United States and Mexico. 
The following table will perhaps assist in the identification of the Central-American 
genera :— 
1. Eyes very deeply divided by a canthus extending halfway across them, 
the antenne inserted near the end of the canthus  . .. . . . . Calopus, 
2. Eyes moderately or feebly emarginate or entire, the antenne inserted at 
or above the inner limit of the eye . . . . woe oe we Be 
3. Penultimate joint of the tarsi very narrowly lobed beneath - + + 4 © Microtonus. ».1\ + 
Penultimate joint of the tarsi broadly lobed beneath . . . . » 4 
4, Anterior tibiz with one spur; antenne 12-jointed in the male, 11 -jointed 
inthefemale . . . . . . . 1. ee ee ee ee ) ~Nacerdes. 
Anterior tibiz with two spurs; antenne 11-jomted in both sexes . . . 5. 
5. Body more or less stout; mandibles bifid; antenne inserted at some 
distance before the eyes; eyes (in our species) small, finely granulated, 
and, usually, rather prominent ; tibial spurs long; claws simple . . . EDitylus. ) Ditu/onre 
Body slender and more parallel . . 2. «© 2. 1. 1. 1. 1 eee 6 
6. Mandibles pointed or entire at the apex * Sse et eye tow ge eae Ne 
Mandibles bifid at the apex. . . . oe ee ee ee 
7. Head not or only a little prolonged in front . oe SO 
Head prolonged in front into a beak; eyes oblong, dempessad; wad finely 
granulated . . . . toa oe - . Piras. p.! 
8. Eyes very large or fioderately ieee, transverse, finely siennlate’ and ; 
prominent; thorax as broad at the base as at the apex; fifth ventral 
segment deeply emarginate in the middle in the male; claws simple . Diplectroides. »'' 
Eyes more oblique, smaller, more coarsely granulated, and not prominent ; 
thorax longer, oblong-cordate, narrowed behind, and narrower at the 
base than at the apex; fifth ventral segment unemarginate in the middle 
in the male; claws toothed or simple. . . . . . . 1... . « «© Owacis. y./*? 
y 
* Sometimes with a short tooth on the inner upper side of the right mandible only. 
qo 
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