NORTH OF MEXICO. 299 



the addition of other tribes the trouble is by no means lessened. In those tribes contain- 

 ing large series of genera, the tendencj to a rapid degradation of form is seen, analagous 

 to the same general degradation of the entire family from the Tentyriidae to the Otido- 

 genae Thus, among the genera of the tribe Tenebrionini forms occur pointing strongly 

 toward an affinity with Helops, and it is here among what might be termed the peripher- 

 ial genera thai doubt may arise as to their true position. 



The separation of the sub-family into Platygenae and Otidogenae has not been followed, 

 as the character seems nol to deserve the importance assigned to it by Lacordaire, and 

 Mr. Pascoe (Ann. and Mag. Nat. Hist., Ser. I V. Vol. Ill, p. 36,) objects to the placing 

 <il' the latter section among the Tenebrionidae, evidently not fully appreciating the fact 

 that this sub-family as denned b) Leconte has a much greater systematic value than anj 

 of the "( !ohorts" of Lacordaire. 



\ c ireful re\ ision of foreign tribes, on the basis of the sub-dh ision of the Family into 

 three sub-families, would result in the union of several. From the limited amount of study 

 I have been able to give them, the Heleides appear to replace in Australia the Blaptini 

 of Europe and America, and should probably form a sub-tribe of Blaptini, in which their 

 p iculiar form would be fully balanced by our species of Embaphion. 



Many changes might be suggested, but as such discussion is altogether irrelevant to 

 the objects el' the present paper, further space will not be occupied h ire, although if is my 

 desire at some future time to develop the results ofstudj in a paper less encumbered with 

 species. 



The following table of tribes is ottered for the assistance of the student, although well 

 aware that it may often fail on the application of the test of several genera and of many 

 species. 



Front entirely corneous, anterior margin free, not articulating with a 

 coriaceous clypeus. 

 first joint of tarsi elongate or moderate, never very short, tarsi not 

 compressed ; genae not sulcate. 

 Eyes less prominent than the sides of trout, more or less transverse, 

 always emarginate in front. 

 Anterior tibia' alone or none dilated. 

 Penultimate joint of tarsi entire. 



Anterior coxae rounded; middle coxa' always with dis- 

 tinct trochantin; antenna' never perfoliate, third 

 joint usuallj larger than the following. 

 Hind coxae transverse, never oblique. 

 Front feebly dilated at the sides. 



