CROCODILIANS, LIZARDS, AND SNAKES. 193 



except in Geckonidie, but it is rudimeutal in some forms, as Phrynosoma. 

 The following- table shows the forms of the pubis in twenty- three genera 

 of different families : 



I. Pubes uniting at an acute angle. 



1. Pectineal process anterior Chamaleon. 



2. Pectineal process median Calotes, Draco, 



Iguana, Dipsoaaurus, Anolis, 



Gerrhonotus, 



Tupinamhiit, Cnemidopliorus. 



3. Pectineal process near acetabulum Scincus, 



Lacerta, 

 Eumeces (rudimental). 



4. No pectineal process Gonyocephalns. 



II. Pubes uniting at an obtuse or very open angle. 



1. Pectineal process median Iguana, Cyclura, Crotaphytus, 



Histiiiriis. 



2. Pectineal process near acetabulum Jgama, 



rhrynosoma, Sauromalus, Sceloporus, 



Heloderma , 



Varanus. 



3. Pectineal process uone Gecko {Phrynosoma, rudiment). 



There is a tuber ischii in all of the genera which have come under my 

 observation except Varanus. In Heloderma and some other forms it is 

 small. 



The anterior limb. — The humerus is much alike in all Sauria, Chamce- 

 leon only presenting peculiarities. The proximal end is expanded 

 nearly in one plane, and the middle portion of the flattened extremity 

 forms the oval head. This is not distinctly isolated, except by the pres- 

 ence of articular surface, from the greater and lesser tuberosities which 

 occupy the angles of the expansion. The shaft betrays no twist. The 

 distal end is chiefly occupied by the condyles; but there are epicou- 

 dyles, of which the internal is the more prominent, except in Cha- 

 ma'leon, where they are wanting. The condyles consist of an external 

 rib and a medio-internal roller, which is generally bounded at the 

 internal extremity by a tuberosity, which is, however, wanting in 

 Chanmleon. The ulna articulates with the median roller, its external 

 edge being beveled by the external rib. The head of the radius articu- 

 lates with the external rib, having shifted from its primitive position 

 on the inner side. It results from this that in pronation the radius 

 crosses the ulna. There is a short olecranon, except in Ghamwleon. 

 The ulna and radius have about an equal share in the carpal articula- 

 tion, sometimes the ulna a little the greater. 



The constitution of the carpus is very uniform in Sauria, with 

 developed anterior limbs, the principal diversity being displayed by 

 the Chamffileonidiie. In all, we have in the proximal row three distinct 

 elements — the radiale, intermedium, and uluare (= pisiforme), the lat- 

 ter mainly external to the ulna and directed posteriorly. Distal to the 

 radiale and intermedium, and between them and the carpalia of the 

 NAT MUS 98—13 



