400 PROCEEDINGS OF THE NATIONAL MUSEUM vol. iii 



published treatments lead to confusion and uncertainty because 

 obliquus shows such extreme variation that one is easily led to believe 

 that but a single variable species is involved. I am not yet fully 

 convinced otherwise, but simply retain the two forms because suffi- 

 cient evidence is not at hand to synonymize a long-established name. 

 Additional specimens, especially from California, should decide the 

 matter. The separating character accepted in the present study is 

 that furnished by the development of the terminal lobe of the 

 peritreme. The large loop- or ear-shaped lobe is accepted as the 

 diagnosis for obliquus, while the reduced lobe marks the distinctness 

 of testudinatus. If the gap would remain evident between these two 

 extremes the two forms could be accepted as distinct. But as indicated 

 by figures 90,b,c, it appears that with a larger series of specimens 

 this gap will eventually be bridged. 



If testudinatus is accepted as being delimited by the reduced 

 peritreme lobe, it appears to be rather uniform in shape, punctation, 

 and coloration of the membrane. But all features for which 

 testudinatus was examined fell within the great range of variability 

 exhibited by obliquus (see specific discussion of variability for this 

 form). The confusion caused by this variability also misled Uhler, 

 who labeled a specimen of obliquus as testudinatus. This specimen 

 does show the proper habitus for testudinatus, but has the loop-shaped 

 lobe on the peritreme and a ventral truncation of the prosternal 

 carinae and lacks the membranal markings. Recourse to the male 

 gonostjdus resulted in no help. In the more than 20 specimens 

 examined, the gonostyli of no two were alike. The series of accom- 

 panying outline drawings (figs. 197,a,6; 198,a-/) demonstrates some 

 of the variability in the shape of this structure. 



Distant's (1880, p. 8) species, Alicroporus mexicanus, appears to 

 be obliquus for three reasons: (1) The generic characterization quoted 

 Uhler's description of the "circular auricle," while the specific descrip- 

 tion said nothing about mexicanus disagreeing on this point (assuming 

 Distant verified the generic features occurring on the ventral surface 

 of his specimens). (2) Distant made a comparison with obliquus, 

 but the differentiating features pointed out that the punctation and 

 wrinkling of the scutellum do not appear to have specific value in 

 the group. In fact, transverse wrinkling appears to be a deformity 

 that occurs often in specimens of this family; perhaps the burrowing 

 of teneral specimens causes the stUl-plastic cuticula to be jammed 

 into folds. (3) The type locality falls within the range of obliquus as 

 accepted here. 



Therefore, at present I recognize as valid within this genus only 

 Uhler's two species and, on the basis of its auriculate peritreme, Berg's 

 Cyrtomenus nigropunctatus. 



