92 MEMOIRS ON THE COLEOPTERA 



seems to be a real and constant difference in the lateral contour of 

 the prothorax toward the basal angles between all four of them and 

 elongatus. 



Duplicatus and costifer, as shown by the convex and obtuse form 

 of body, peculiar outline of the prothorax, narrow side margins 

 and twin lateral carinae of the elytra as well as the long humeral 

 carinse of the depressus and elongatus groups distinguishing them 

 from any of the obsoletus group,- form a natural and isolated 

 division of the genus; they differ from each other specifically and 

 are not related subspecifically, as very conservatively maintained 

 by LeConte in later years. 



The El Paso male and Marfa female, which I have placed provi- 

 sionally with the type of vestigialis, are probably different, forming 

 at least a subspecies; they do not have a trace of the faint lines of 

 punctures seen in the New Mexican type, taken by Prof. Snow, and 

 are a little more convex. I am also of the opinion that the two very 

 smooth and impunctate examples, placed above with the rather 

 conspicuously punctate two typical specimens of corpidentus, 

 represent a closely allied but different taxonomic form. Larger 

 series are desirable however. 



Viridans Lee., was said by the author (1. c.) to be a variety of 

 mexicanus, but this was contradicted by Bates in the "Biologia." 

 The form described above under the name ambiens, differs markedly 

 from viridans in sculpture, as well as some other characters, and 

 may be more than subspecifically different, for species in this group 

 having brilliant green margins, are probably not limited to mexi- 

 canus and viridans alone, although the peculiar coloration is of a 

 highly specialized type in the genus. 



The left mandible is nearly always more strigose than the right 

 in this genus and the strigosity is limited to a smaller area in the 

 male than in the female ; there are also other singular sexual differ- 

 ences hitherto unobserved, mentioned above in several instances, 

 such as the general convexity of the upper surface in the depressus 

 group and the supplemental dentition of the mandibles in ambiens 

 and others. The complete absence of the basal groove of the pro- 

 notum in perpolitus a character so universal in the genus is an 

 interesting peculiarity of that species. 



