E.N. ARNOLD 



Fig. 10 Left side of tail base in P. roborowskii, showing enlarged spinose 

 scales. 



developed in males than females. Tubercles are frequently 

 clumped, especially anteriorly, and there is considerable varia- 

 tion in the number associated in such groupings. Tubercle form 

 is also variable and is especially narrow, pointed and elongate in 

 P. forsythii, which also shows particularly strong sexual dimor- 

 phism. Although the presence of tubercles is usually a clear-cut 

 condition, their development is sometimes sporadic and weak. 

 For instance, many P. theobaldi lack them but a few animals 

 have somewhat enlarged scales that are raised and form weak 

 tubercles posteriorly. 



30. Scales at sides of tail base distinctly enlarged and often spinose 

 (Figure 10). No (0); yes (1) 



31. Horizontal fringe of pointed upturned scales on posterior sur- 

 face of proximal thigh. No (0); yes (1). 



32. Subdigital lamellae on distal part of fourth toe of pes (Figure 

 11). With two or more keels or at least projections from the free 

 edges of the lamellae (0); with a single keel or none (1; 



33. Narrow light longitudinal stripes often present on flanks. No (0); 

 yes(l). 



34. Dark pigment frequent in mid-line area of belly in adults. No (0); 

 yes(l). 



35. Distal tail often with substantial dark pigment at least ventrally, 

 where it may form transverse bars. No (0); yes (1). 



Soft parts 



36. Palatal flaps. Large (0); reduced or absent (0) 



37. Tympanum. Well developed and robust(O); reduced to a delicate 

 membrane (1); absent (2). This and other ear features of 



Fig. 11 Underside of fourth toes of pes (anterior edge above), showing 

 extent of lateral fringes of pointed scales and number of keels on 

 subdigital lamellae, a. Fringes small, especially anteriorly, two keels 

 distally (P. theobaldi). b. Large fringes, single keels (P. mystaceus). 



Bufoniceps and Phrynocephalus are discussed further elsewhere 

 (Arnold, submitted). 



38. Pars inferior of extracolumella. Large (0); small or absent (1) 



39. Pharyngeal opening of middle ear. Large, length 15-25% of 

 head length (0); distinctly reduced, length about 10-14% of 

 head length (1); minute or absent (2). 



40. Episterno-cleidomastoideus muscle present (Figure 12). Yes (0); 

 very reduced (1); absent (2). 



41. Episterno-cleidomastoideus muscle a single strap (Figure 12). 

 Yes (0); with two branches (1). 



42. Episterno-cleidmasoideus muscle extends anteriorly to occiput 

 (Figure 12). No (0); yes (1). 



43. Scapulodeltoideus muscle extends upwards immediately ante- 

 rior to insertion of acromiotrapezius muscle on scapula. No (0); 

 yes(l). 



44. Origin of caecal artery on doral aorta (Figure 13). Anterior and 

 close to mesenterica cranialis artery and well posterior to coeliac 

 artery (0); close to and usually in front of coeliac artery, occasion- 

 ally behind (1). 



The caecal artery, which arises from the dorsal aorta and sup- 

 plies the intestine, exhibits interspecific variation in the position 

 of its origin on the aorta, relative to the origins of the coeliac 

 artery, which runs to the stomach, and the mesenterica cranialis 

 artery, which like the caecal artery supplies the intestine (Henke, 

 1974). In at least someSitana andDraco, and inAcanthocercus, 



acromiotrapezius 



occiput 



episterno- 

 cleidomastoideus 



scapulodeltoideus 



Fig. 12 Diagramatic representations of superficial muscles of the right shoulder and neck. a. Episterno-cleidomastoideus muscle a single strap not 



extending to the occiput; no dorsal extension of scapulodeltoideus muscle anterior to insertion of acromotrapezius muscle, b. Episterno-cleidomastoideus 

 muscle divided, the anterior branch reaching the occiput; a dorsal extension of scapulodeltoideus muscle anterior to insertion of acromiotrapezius muscle 

 present. 



