96 Proceedings of the Biological Society of Washington. 



Geographical probabilities thus favor the supposition that the type was 

 of the smaller species, but the matter is complicated by the discovery that 

 certain specimens from the San Joaquin Valley are practically indistin- 

 guishable from the smaller species and suggest the possibility that both 

 species occur throughout that region. These small specimens are found 

 in relatively small numbers at localities where the large species has been 

 taken in series. Out of nearly 200 specimens examined from the San Joa- 

 quin Valley only nine are small. These are as follows: Fresno 2; Lodi 

 3; Marysville Buttes 1 ; Oakdale 1 ; Three Rivers 2. Attempts to account 

 for these small specimens on the basis of sexual or individual variation 

 have not been thoroughly satisfactory. Moreover, it is practically im- 

 possible to distinguish them by cranial characters from specimens from 

 the Tejon region. As compared with the larger species of the San Joaquin 

 Valley (inornatus) they are characterized by smaller size, smaller mas- 

 toid bullae, narrower braincase, less mastoid width, slightly shorter nasals, 

 less width across parieto-frontal suture, and always greater relative and 

 usually greater actual width across the interorbital space. No single one 

 of these characters is very pronounced but all are so constantly correlated 

 that after careful study one finds it difficult to believe they are not of 

 specific significance. 



The type of longimembris , which was placed with the larger species on 

 account of a rather narrow interorbital space, now seems clearly to belong 

 to the smaller form. Its interorbital space, although actually narrow, is 

 relatively about the same width as in other examples of the smaller species 

 and it agrees with them in the other cranial characters above mentioned. 

 The type is preserved in alcohol, the skull having been removed and 

 cleaned in recent years. The skin is in poor condition and identification 

 depends wholly upon the skull which is that of an immature animal. 

 Among recent specimens, the one most closely resembling the type is an 

 adult female collected in Tejon Canyon by Luther J. Goldman in July, 

 1903, and now in the Biological Survey collection. It has the crowns of 

 the molars worn flat and, although much older than the type, agrees 

 with it very closely. 



It seems, therefore, that the name Perognathus inornatus should be 

 revived for the larger species of the San Joaquin region, its one subspecies 

 being Perognathus inornatus neglectus. The name longimembris should 

 again be used for the small species of the Tejon region, P. elibatus and 

 perhaps P. brevinasus being synonyms. Closely related subspecies are 

 P. 1. panamintinus, P. I. bangsi, and P. I. arenicola, while later study 

 very probably will show that P. nevadensis and P. pericalles should be 

 added to these. — Wilfred H. Osgood. 



