424 Materials for a Monograph 



Bacteria femorata, Haldeman in Icon. Encyc. (1857.) 



Bacunculus femoratus^ Uhler in Harris, Inj. Ins., 3d ed. ; 



146. (1861.) 



Mass., (H. Coll., Sanborn, S. H. S.) N. H., (H. Coll.) 

 Illinois, (Uhler.) Red River Settlements, British America, 

 (S. H. S.) Nebraska, (Mus. Comp. Zool.) 



GRYLLTDES, Latreille. 

 TRIDACTYLUS, OLIVIER. 



The fact that this name is inapplicable in its significa- 

 tion to some of the species contained in it, is no valid rea- 

 son for its disuse ; and even should it be so considered, the 

 name Heteropus proposed as early as 1805 by Palisot de 

 Beauvais, must supersede that of Xya> so commonly in 

 use, which was not proposed till four years later. If, 

 however, the species having but two of the slender appen- 

 dages at the termination of the posterior tibiae should be 

 found to differ generically from those having three, Tri- 

 dactylus would have to be retained for the latter, with 

 Heteropus as a synonym ; and Xya should be applied to 

 the former. That this may yet be found to be the truth, 

 is indicated still further by the fact that the three-fingered 

 species found in this country have a peculiar conformation 

 of the anterior tibiae, which, however, is a feature of the 

 structure of the male alone, a fact for which I am in- 

 debted to the scrutiny and kind communication of Mr. 

 Uhler; this peculiarity is a lateral projection of an ad- 

 uncate appendage inwards at the base, to the extremity of 

 which, beside the hook, the tarsi are attached. As a fig- 

 ure will explain much better than any description I can 

 give the form of these parts, I have drawn the anterior 

 tibiae and tarsi of T. apicalis. Say <. In the two 

 species (T. apicalis, Say, and T. terminalis, Uhl.) 

 which show this character, a further difference is to 

 be seen between the males and females, in the more 

 swollen prothorax of the former. 



