CRYPTOCEPHALUS IN AMERICA NORTH OF MEXICO ^ 



beneath; the third segment is bilobed. The last segment is rather broad 

 apically, and the claws are divergent and simple. 



Sexual characters: The most reliable character for distinguishing the 

 sexes is the form of the fifth abdominal segment. In all femalesrthis 

 segment bears a distinct, deep depression at the center. The depre'ssion 

 is nearly always broad and sharply margined anteriorly; there is often 

 a rather long series of hairs arising from the anterior margin of the 

 depression. In striatulus Leconte, this depression is less developed tlian 

 usual but is stiU quite distinct. The fifth abdominal segment of the 

 male at its center is convex to flat or even slightly depressed. Also, 

 there are often sexual differences in the development of the anterior 

 margin of the prostemum. When these occur, the male tends to bear a 

 spine, and the female bears a lobe. Sometimes both sexes bear a lobe 

 but that of the male is more pointed than that of the female. In a few 

 species, there are distinct to barely detectable sexual differences in 

 the color or color pattern; also, in some species, males are smaller than 

 females. The color and size differences can sometimes be used for rapid 

 sexing of specimens. In mutahilis Melsheimer and insertus Haldeman, 

 nearly all males can be distinguished from females on the basis of these 

 characters. In mntabilis, small individuals with the black markings 

 are invariably males, and large individuals with the dark reddish 

 markings are females. In insertus, the males are generally smaller and 

 have more complete dark markings than the females. In both venustus 

 simplex Haldeman and v. ornatulus Clavareau, the color patterns of 

 the sexes are quite distinct. Unfortunately, the males of both these (I 

 beUeve) are identical to the males of v. venustus F. In some species 

 that show a distinct difference in the sizes of the sexes, there may be 

 Uttle or no overlap in length, but this has not been explored thoroughly. 



Genitalia: The male genitalia of selected species have been extracted, 

 cleared in KOH, and illustrated (figs. 112-140). Included are new 

 species, their nearest relative, many of the new subspecies, and at least 

 one member of species groups not represented by any of the former. 

 Representatives of different species groups can often be distinguished 

 on the basis of external appearance of these parts, but the genitalia of 

 related species usually do not offer useful external characters. Once 

 the genitalia are cleared, the internal processes become visible, and 

 these offer characters useful in distinguisliing species. I have found 

 generally that the subspecies of a species show little or no differences 

 in the internal and external form of the parts; for example, the geni- 

 taHa of the subspecies of venustus are essentially identical; the same is 

 true of the subspecies of notatus F. 



Notes on the important findings resulting from the genitahc work 

 are included under the appropriate species. The illustrative technique 

 used to portray the genitalia (Coquille board) has been found ideal for 



