86 Clark The Short- Mouthed Snake. 



third and fourth as in brachystoma; while .the deep brown band 

 below these stripes is wanting in sirtalis. The difference in 

 form is equally noticeable, though less easily stated; brachy- 

 stoma is more stocky and tapers towards both ends rather 

 abruptly. As regards the number and arrangement of scales, 

 the two species are equally distinct, although individuals occur 

 combining the characters curiously. Thus No. 5 has 7 upper 

 labials on each side, the normal number for sirtalis, while No. 4 

 has 9 lower labials on the left side; out of 320 specimens of sir- 

 tolls examined this spring, 6 have 6 upper labials on one side 

 but none have that number on both sides, while 1 2 have 8 upper 

 labials on one side, and 2 have that number on both sides; as re 

 gards the lower labials, 268 of the 320 have the lower labials 10 

 on each side, 9 have 9 on each side, 4 have 1 1 on each side, and 2 

 have only 8 on each side, while the remainder have 9 or 11 on 

 one side or the other, except 3 which have 8 on one side. The 

 most interesting case in this connection is a small male sirtalis, 

 which has the upper labials 67 and the lower 88; however, as 

 it has 152 gastrosteges and 75 urosteges and is a perfectly nor 

 mal sirtalis in coloration, it cannot be regarded as in any sense 

 a connecting link with brachystoma. In the number of gastro 

 steges the difference between the two species is striking, brachy- . 

 stoma ranging from 132 to 141, with an average of about 136, 

 while the 320 specimens of sirtalis range from 142 to 159 and 

 average about 151; and it should be added that of the 320, only 

 one has 142, two have 143, and two 144 gastrosteges. In the num 

 ber of urosteges the two recorded male brachystoma are far apart, 

 61 and 72, an average of less than 67, but male sirtalfe range 

 from 64 to 79, with an average of more than 71, and further, 

 only 9 of 163 specimens have less than 67 urosteges; the female 

 brachystoma range from 52 to 58 with an average of more than 

 55, while female sirtalis range from 57 to 73, with an average 

 of more than 63, and only 4 out of 157 have less than 59. 

 Cope's statement that "the number of urosteges remains as in" 

 sirtalis requires, therefore, some modification, as it is clear that 

 the number is normally decidedly less than in the common gar 

 ter-snake. 



In regard to the habits of brachystoma^ Cope's statement that 

 "it is one of the forms * * * which * * * have 

 adopted a terrestrial life and more or less burrowing habits" is 



