CEDEMERID^: OF BOREAL AMERICA. 383 



mixed; this, together with the necessity for the correction 

 of errors noticed by Mr. Champion and myself, and the 

 presence of a fair number of new species needing de- 

 scription, has suggested the propriety of presenting a 

 new study of all our species, that they might properly be 

 compared with each other. 



The study of Oxacis was particularly interesting. As 

 constituted by LeConte, it was to contain species with 

 simple mandibles, simple claws, two tibial spurs, and 

 eleven-jointed antennae. LeConte, however, included 

 one species in which the right mandible was not simple, 

 but with a tooth on the upper side. 



On the other hand those species with a toothed claw 

 were separated as Probosca, which Mr. Champion has 

 shown to be incorrect, and my observations have con- 

 firmed. Mr. Champion also finds that species must be 

 admitted in Oxacis with both toothed and simple claws. 

 Our species do not exhibit intergrades but the Mexican 

 forms do. At this point it might be observed that the 

 only valid difference between Copidita and Asclera is 

 that the first has simple claws and the latter toothed. I 

 cannot, however, consent to admit that dorsalis and its 

 allies can be included in Oxacis. The so called toothed 

 right mandible of that species is really a bifid mandible 

 in which the upper tooth is a little shorter to permit 

 proper articulation with the absolutely simple left mandi- 

 ble. This structure seems to me exactlv intermediate 

 between those species with both mandibles bifid and both 

 simple, and to include such a structure with both simple 

 and toothed claws in one genus is not only unnatural and 

 confusing, but also suggests the thought that all three 

 genera should be united. The better course has seemed 

 to be to separate these heterogeneous forms as a distinct 

 genus. 



