138 GEO. H. HORN, M. D. 



Next In order we have the g-roup Rhizotrogi, containing five genera 

 separated in the following manner : 



Claws never serrate, with a single tooth beneath. 

 Ligula deeply emarginate. 



Antennae 10 -join ted EugastrR. 



Antennae 9-jointed Eudrosa. 



Ligula nearly truncate. 



Labrum bilobed l<-itchnO!$terna. 



Labrum concave, not bilobed Gyiiiiis. 



Claws more or less serrate, sometimes toothed Liisti'OClieltlS. 



The emargination of the ligula, as far as its use for generic separa- 

 tion is concerned, is not a valid character, very many well known and 

 acknowledged species of Lachnosterna possess it in a varying degree 

 from a feeble notch to a well defined emargination. The species of 

 Eugastra must therefore take place in Lachnosterna near farcta and 

 laiiceolata. The two species of Endrosa take remote places in Lach- 

 nosterna ; quercns as a distinct group near suhnuiclda ; vohula near 

 frontalis where Dr. Leconte originally intended to place it. (Synopsis 

 p. 2.39). Gi/nnis is based on a species with the labrum concave and 

 not bilobed. It will be necessary merely to examine the labrum of 

 the species of the longitarsis group of Lachnosterna to become con- 

 vinced not only that the character has no value but also that the 

 species {dehilis) belongs there. An examination of the labrum of 

 glahripennis might also add weight to the above. 



Having thus rather summarily united five genera by the suppression 

 of four it becomes necessary to defend the sixth, which, from the 

 characters given in the books, seems to have the least claim of all 

 to be retained. 



lilSTROCHELiUS Blanch. 



Head with a carina on the vertex extending from one side to the 

 other slightly posterior to the anterior margin of the eye. Free angle 

 of coxal plate acute and slightly prolonged. Claws frequently pecti- 

 nate or serrulate. 



These three characters or any two of them together serve to sepa- 

 rate Listrochelus from Lachnosterna. 



The carina on the vertex seems to be the most important, and is 

 absent entirely in one species only (^senex), and may be partially 

 obliterated at its middle but visible at the sides. This carina is not 

 of the same character as that seen in Aplidia where it is frontal and 

 as far as can be seen merely a matter of sculpture or ornamentation, 

 while the carina of Listrochelus is so placed as to restrict the retractile 



