76 BULLETIN 17 5, UNITED STATES NATIONAL MUSEUM 



m. ruthveni has the dorsum pale brown with 50 chocolate-brown spots 

 on the body and tail. 



From the forms of the deppei group ruthveni may be separated 

 readily by the presence of four, rather than two, prefrontals, by the 

 contact of a single preocular with the eye on either side, instead of 

 two, and by the elongated rostral, which is twice as long as broad in 

 ruthveni, while it is at least as broad as long m the three forms of the 

 deppei group. 



From all other forms of the genus ruthveni may be distinguished 

 by the longer rostral, which is never twice as long as broad except in 

 the subspecies of melanoleucus, and by the pattern. Thus, in ruthveni 

 the ground color is decidedly brownish, and the anterior spots are 

 much smaller than the posterior ones, while in the other forms under 

 consideration the ground color is always yellowish white, forming a 

 marked contrast with the dark spots, and the spots are more or less 

 uniform in size throughout the length of the body. 



Description. — Since the description of this form (Stull, 1929, p. 1) 

 no specimen has been reported in addition to the original two. 

 [A specimen was collected by Burt (1935a, p. 381) at Za valla, Angelina 

 County, Tex., which "resembled sayi of more western and northern 

 areas so closely that it was presumed to be that form until it was 

 identified in the laboratory. Here it was soon found to have the 

 reduced number of dorsal saddles or blotches assigned to 'P. melanoleu- 

 cus ruthveni' by Stull (1929), rather than the higher number specified 

 for the form which was termed *P. sayi sayi' in the same publication. 

 This led to the identification of the specimen at hand as ruthveni ..." 

 No distinction between these two forms on the basis of the number of 

 dorsal spots was mentioned in the paper cited (Stull, 1929, p. 1), 

 and none has been found to exist, the number of spots in s. sayi in 

 the specimens examined ranging from 41 to 84, while the type of 

 m. ruthveni has 50. The distinction, as described above, lies rather 

 in the proportionate length of the rostral, and in coloration and 

 pattern. This specimen, therefore, should undoubtedly be referred 

 to sayi, of which it appears to be a typical example.] Of the two 

 specimens known, the type is described above, and the second speci- 

 men will be considered below under the discussion of variation. 



Variation. — The paratype of this form, another male, is from the 

 same locality as the type. It differs from the type in having the 

 dorsal scale formula 31-31-22, ventrals 218, caudals 60, supralabials 8, 

 infralabials 14, postoculars 3, and the tail length 0.131 of the total 

 length. The specimen is so badly preserved as to render the number 

 of dorsal spots indistmguishable, but the general scheme of coloration 

 closely resembles that of the type specimen. 



Range. — Known only from the type locality. 



