SNAKES OF THE GENUS PITUOPHIS 143 



total length. The longest specimen examined measured 1,630 mm. in 

 length. 



The dorsal scale formula varies from 27-29-21 to 31-37-27. The 

 number of scale rows at the neck is 25 to 33, usually 29 ; the maximum 

 number of rows in the middle of the body 29 to 37, most often 31 ; the 

 minimum number anterior to the vent 21 to 27, usually 23. The 

 remaining scutellation is as follows: Ventrals 206 to 234 (average 

 220.3); caudals 54 to 80 (average 66.4); supralabials usually 8, fre- 

 quently 9, occasionally 7 or 10, with the fourth usually, fifth occasion- 

 ally, sixth or none rarely, entering the orbit; infralabials 10 to 14, 

 usually 12 or 13; preoculars 1 to 3, uually 2; postoculars 2 to 6, most 

 often 3; loreal usually present, occasionally divided to form two or 

 even three small scales; azygos present occasionally between frontal 

 and prefrontals, rarely between prefrontals and preocular on either 

 side ; rostral low and broad, at least as broad as long, and penetrating 

 from one-third of to aU the distance between the internasals; frontal 

 never divided. 



The dentition is as follows: Mandibular teeth 16 to 19, decreasing 

 slightly in size posteriorly; maxillary teeth 14 to 17, decreasing slightly 

 in size posteriorly ; palatines 7 to 11, slightly smaller than the mandibu- 

 lar and maxillary teeth ; pterygoids 7 to 14, decreasing slightly in size 

 posteriorly, sUghtly smaller than the palatines. 



The dorsum bears a series of median, brown, grayish-brown, or 

 black spots, which are quadrangular or bar-shaped, and number 44 to 

 94 (average 66) on the body and 12 to 31 (average 21.1) on the tail. 

 Each spot is 1 to 5 scales long and 7 to 1 1 scales wide, and the inter- 

 spaces between the spots are 1 to 3 scales long. Frequently the spots 

 are partly or completely outlined narrowly with black. There are 

 three series of smaller dark spots on either side, which alternate with 

 one another and with the dorsal series. The spots of the uppermost 

 lateral series are darkest and largest and are frequently outhned with 

 black. The lowest series has the smallest and palest spots. The median 

 lateral series frequently has the scales between the spots slightly darker 

 than the surrounding ground color, forming a more or less continuous 

 pale-brown stripe dotted at regular intervals with the spots of the series. 

 The ground color of the dorsum is yellowish white or pale brown ; of 

 the belly, white. The belly bears a series of lateral spots on either side, 

 each K to 1 scute in length and separated by 1 to 4 scutes, or rarely 

 occurring on several successive scutes. The belly may be immaculate 

 between the lateral series of spots or irregularly spotted for part or all 

 of its length. The top of the head is pale brown, more or less dappled 

 with darker brown, and usually bears a transverse band of dark brown 

 between the eyes, on the anterior part of the supraoculars and frontal, 

 and the posterior part of the prefrontals. Dark streaks occasionally 

 mark the sutures between the supralabials and between the infra- 

 labials. The throat is white. (Fig. 64, h.) 



