464 SYDNEY E. JOHNSON 



be seen above each occipital spine. Small dark patches are ar- 

 ranged radially around the orbit. On the tip of the lower lip is 

 a dark blotch, and fine black dots line the under edge of the 

 mandible. The superior surface of the head is covered with dark 

 spots and wavy bars to within a short distance of the occiput 

 (fig. 1). 



B. INTEGUMENT 



The skin is relatively thick and tough. It is everywhere cov- 

 ered with minute papillae which are smaller and more numerous 

 on the head than on the body. On the body there are approxi- 

 mately 400 papillae to the square centuneter, and they range 

 from 0.5 to 1 mm. high about by 0.2 mm. in diameter. 



The scales are represented by multipointed spinous processes, 

 each arising from a polygonal bony plate which is buried in the 

 skin beneath a papilla. Near the tip of the papilla the spinous 

 process divides into a number (two to five) of sharp prickles which 

 pierce the distal end of the papilla (figs. 2 and 3). 



C. SKELETAL SYSTEM 



1. Cranium 



The basioccipital (bo.) is expanded posteriorly to form the 

 deeply concave body of the occipital condyle. On its ventral 

 .side is a deep keel-like process running posteriorly to articulate 

 with a similar process of the parasphenoid. It is separated from 

 the exoccipital by a longitudinal suture which passes forward 

 just below the auditory capsule. Posteriorly the suture passes 

 between the large centrum of the basioccipital and the articular 

 facet of the occipital. The posterior part of the basioccipital 

 thus fonns a narrow part of the ventral boundary of the foramen 

 magnum (figs. 5, 7 and 8). 



The exoccipitals (eo.) are relatively large bones bearing well- 

 developed zygapophyses and, laterally, they are perforated for 

 the vagus nerves. The exoccipitals, together with the basiocci- 

 pital, form the entire boundary of the foramen magnum. Each 

 exoccipital bone is separated from the prootic on its side by a 



