SNAKES OF THE GENUS PITUOPHIS 187 



the anterior part of the body each with a small central black spot, 

 while such markings are generally lacking in annectens. 



Description. — The body is rather slender, and the snout is rather 

 blunt. The tail varies from 0.135 to 0.182 (average 0.161) of the total 

 length and is thus proportionately longer than that of any other 

 form of the genus. The longest specimen examined measured 1,620 

 mm. in length, but Klauber (1931, p. 70) reports one measuring 1,739 

 mm. (5 ft. 8K in.) long. 



The dorsal scale formula varies from 29-29-21 to 33-37-25. The 

 number of scale rows at the neck is 27 to 33, usually 29 or 31; the 

 maximum number in the middle of the body 29 to 35, oftenest 33; 

 the minimum number anterior to the vent 21 to 25, usually 23 or 25. 

 The remaining scutellation is as follows: Ventrals 210 to 253 (average 

 229.4); caudals 60 to 84 (average 74.1);supralabials 7 to 10, usually 8 

 or 9; the fourth, fifth, or none entering the eye; infralabials 11 to 15, 

 usually 12 or 13; preoculars 1 to 3, usually 2; postoculars 3 to 5; 

 loreal present, frequently divided to form two or even three small 

 scales; azygos present between frontal and prefrontals in about 10 per- 

 cent of the specimens examined, occasionally present between pre- 

 frontal and preocular on either side, between the two pairs of pre- 

 frontals, or behind the rostral; rostral low and as broad as long, 

 penetrating usually from one-third to all the distance between the 

 internasals ; frontal usually undivided but rarely split for a very small 

 fraction of its length. 



The dentition is as follows: Mandibular teeth 18 to 20, decreasing 

 slightly in size posteriorly; maxillary teeth 14 to 18, decreasing slightly 

 in size posteriorly; palatines 9 to 10, slightly smaller than the mandib- 

 ular and maxillary teeth; pterygoids 8 to 14, sUghtly smaller than the 

 palatines and decreasing slightly in size posteriorly. 



The dorsum bears a series of dark brown, dark gray, or black spots, 

 each 1 to 4 scales long and 4 to 8 scales wide, separated by interspaces 

 of 1 to 3 scales each and numbering 55 to 92 (average 75.5) on the 

 body and 14 to 36 (average 24.0) on the tail. On each side there 

 are four or five lateral series of dark spots. The uppermost of these 

 series is composed of spots nearly as large as those of the dorsal series, 

 with which they fuse at the corners to form a more or less continuous 

 network, presenting the appearance of a complete or broken chain. 

 On the neck and for a short distance posterior one or more of the 

 lateral series have the spots fused to form one or more continuous 

 or broken longitudinal streaks. The lower rows of lateral spots are 

 more or less irregular and indistinct in many specimens and are always 

 paler than the dorsal and uppermost lateral series. The ground color 

 of both dorsum and belly is a yellowish white, with pale brown often 

 shading the interspaces between the dorsal spots and forming a more 



136423—40 13 



