1912] Taylor: A New Perognathus 159 



and Ripon, San Joaquin County; Oakdale, Stanislaus County; 

 Livingston, Merced County; Huron, Fresno County; Three- 

 rivers, Tulare County; and Walker Basin, Delano, and Bakers- 

 field. Kern County. Consequently the range of Perognathus I. 

 longimembris may be said to be the Lower Sonoran and lower 

 Upper Sonoran zones of the San Joaquin Valley, except the 

 southwestern portion. 



STATUS 



Perognathus longimembris neglectus is the largest member 

 of the panamintinus group in California, in size equalling Pero- 

 gnathus amplus Osgood (from Fort Verde, Arizona). It is cer- 

 tainly, as would be expected, most closely related to its nearest 

 neighbor, longimembris, and for the following reasons: (a) In 

 general coloration it is very close to longimembris; (b) the lat- 

 ter form, as regards size, approaches it more closely than does 

 any other member of the panamintinus group in California; 

 (c) the skull is in the main similar, though larger; (d) the geo- 

 graphical probabilities so indicate. 



Neglectus need be confused with no other member of the 

 panamintinus group. Larger size serves to distinguish it from 

 /'. [i. panamintinus C. II. Merriam. From I', p. bangs! Mearns 

 it is differentiated by a more ochraceous-buff coloration and 

 larger size. Lighter coloration and larger size separate it from 

 P. p. brt vinasus Osgood. The uniformity of coloration which 

 is so evident in longimembris (see Osgood, 1900, p. 33) is em- 

 phasized to a still greater degree in neglectus. 



The question arises as to the status of the new form from the 

 current point of view of processes of evolution. Is it merely an 

 environmentally induced geographic race or an ontogenetic one, 

 of such a nature that, were it transported into the area inhabited 

 by Perognathus I. longimembris, it would revert immediately to 

 the type exhibited by that subspecies? Or does it represent a 

 true germinal variant? Experimental investigation might fur- 

 nish illuminating data on these points. 



It is possible that isolation has been a condition in the 

 differentiation of the two forms. Buena Vista Slough, which 

 probably constitutes a partial barrier, extends from Tulare Lake 



