526 PROCEEDINGS OF THE NATIONAL MUSEUM vol. iii 



A grouping similar to the one based on the degree of dilation of the 

 posterior tibia is possible if reference is made to the presence or absence 

 of a postmedian, partial row of prominent setigerous punctures on 

 the lateral third of sternites IV to VI, as indicated in the following 

 couplet: 



With setigerous punctures on lateral third of 

 sternites IV to VI : cilialus (Palisot de Beauvois) 



crassus Walker 

 Without such setigerous punctures: mirabiUs (Perty) 



bergi, new name 



One notices immediately that mirahilis is the form that shifts position 

 in these various associations. Obviously, it is not an extreme form, 

 but probably occupies a somewhat intermediate position. In habitus 

 it appears closest to the two North American forms, but is separated 

 from them on the absence of setigerous punctures on the lateral third 

 sternites IV to VI and the less expanded hind tibia. The latter 

 feature should not be passed over too lightly, because if one of the 

 directions of evolution within the Cydnidae is towards greater efficiency 

 of digging (which seems logical in view of what is known of the ecology 

 of the group) the more strongly dilated posterior tibiae should have 

 some significance within this subgenus. 



Key to species of the subgenus Cyrtomenus (Cyrtomenus) 



1. Sternites IV to VI with postrnedian, partial, transverse row of prominent 



setigerous punctures on lateral third; posterior tibia strongly compressed, 

 its greatest diameter nearly or quite equal to that of anterior tibia ... 2 

 Sternites IV to VI without a transverse row of prominent setigerous punctures 

 on lateral third; posterior tibia weakly to moderately compressed, greatest 

 diameter not more than two-thirds that of anterior tibia 3 



2. Outline ^ of juga rounded, tending to be somewhat triangular (fig. 56) ; about 



one-half width of eye projecting laterally beyond posterolateral angle 



of jugum ciliatus (Palisot de Beauvois) (p. 530) 



Outline of juga verybr oadly rounded and rcflexed (fig. 57) ; about one-third 

 of eye projecting laterally beyond posterolateral angle of jugum. 



crassus Walker (p. 533) 



3. Space separating ocellus from eye less than transverse ocellar width (12:20); 



surface of head distinctly convex, with coarse, radiating rugae 



mirabilis (Perty) (p. 536) 

 Space separating ocellus from eye slightly more than transverse ocellar width 

 (18: 15) ; surface of head nearly smooth, almost without rugae 



bergi, new name (p. 527) 



' Note: When using this feature, one is cautioned to determine the amount of wear on the margin of the 

 head by noticing the position of the margin of the head in relation to the submarginal row of setigerous 

 punctures. This character may be negated by such wear. During the present study, it has been noti ed 

 that there appears to bo a direct correlation between the amount of wear on the marginof the head and that 

 shown by the dorsal margin of the anterior'tibia. In extreme cases, even the tubercles that give rise to the 

 dorsal spines of the anterior tibia may be completely abraded away. Such a situation may be used as a 

 check for the amount of wear on the margin of the head. 



