AMERICAN COLEOPTERA. 139 



capability of the "head, for, when the head is withdrawn it rests against 

 the anterior margin of the thorax. 



The prolongation of the free angle of the coxal plate is a constant 

 character in the present genus and singularly it is present in Aplidia 

 also. In all our Lachnosternx the angle is at most rectangular, some- 

 times obtuse never prolonged. 



The pectination of the claws although not by any means constant 

 is peculiar to the genus. The tables of the two sexes which follow 

 give the details in brief. In those species in which the claws are 

 decidedly pectinate and not merely serrulate, the claw is stout and its 

 lower edge is double, or rather there are two edges separated by a deep 

 groove; these are both pectinate, the proximal side of each claw, or 

 that which is nearest to its fellow, has the edge which is most feebly 

 pectinate, the outer edge being most strongly pectinate and bearing 

 the tooth when it exists. This double pectination is peculiar to the 

 male. In the females of these males there may be seen traces of the 

 double edge but never serrulate or pectinate. One species has strongly 

 pectinate claws with the pectination single, that is, from one margin 

 only. The other peculiarities of the claws are spoken of at suflBcient 

 length in the descriptions. 



The antennae are always 10-jointed, the joints 3 — 7 varying consider- 

 ably in length in the different species. I have not mentioned these 

 variations because I have little faith in their constancy. There are now 

 twelve species in our fauna, five of which are mentioned here for the 

 first time, of the eight previously known one has been suppressed. 



The accompanying tables have been prepared at the cost of con- 

 siderable time and labor and show a remarkable parallelism. They have 

 been arranged for each sex in such a manner that the more special- 

 ized types as indicated by the structure of the claws, begin the table, 

 each succeeding species showing a regular gradation from this through 

 the forms of claws of other genera to the simple type of Scarabaeide 

 claw, a character of rare occurrence among the Rhizotrogi. 



A supplementary table is also given, the use of which will be seen, 

 it contains those species not in both the sexual tables. 



Table fur the distinction of known males. 

 I. — Claws of anterior and posterior tarsi pectinate. 

 Claws all pectinate without tooth. 



Pectination arising from a double margin. Thorax sparsely punc- 

 tured (lisparilis. 



Pectination from a single margin only. Thorax vei'y densely punc- 

 tured puberulus. 



