342 CLASS REPTILIA. 



The pectoral girdle is always present, even when the fore- 

 limbs are absent, though it may be much reduced and not reach 

 the sternum.* Typically (Figs. 187 and 188) it consists of a 

 suprascapula, scapula, and coracoid which articulates with the 

 sternum ; and of a clavicle, and interclavicle. The scapula and 

 coracoid are partly ossified and fenestrated. Clavicles and 

 interclavicle are absent in the chameleons, and in some of the 

 limbless forms. 



The manus usually possesses five digits, in which case the 

 carpus consists of eight bones, an ulnare, radiale, centrale, 

 and five distal bones. 



The pelvic girdle consists of ilia which articulate with the 

 two sacral ribs, and pubes and ischia which meet in a ventral 



/i.cr 



FIG. 187. Side view of the pectoral girdle and sternum of Iguana tuberculata (from Huxley). 

 cl clavicle ; cr coracoid ; e.cr epicoracoid ; gl genoid cavity ; i.cl interclavicle ; m.cr ineso- 

 coracoid ; m.sc mesoscapula ; p.cr precoracoid ; s.sc suprascapula ; st sternum : x.st xiphi- 

 sternum. 



symphysis. The pubo-ischiadic foramen is only divided by 

 ligament. There is usually a cartilaginous (or calcified) epipubis, 

 and a cartilaginous continuation of the ischiadic symphysis 

 backward, to support the cloaca (hypo-iscMum or os cloacae}. In 

 the limbless forms the pelvic girdle may undergo great reduc- 

 tions, but no part appears to vanish entirely ; and the sacral 

 connection is preserved, except in the Amphisbaenidae. 



The pes usually possesses five digits. In the tarsus there is a 

 tendency to an intertarsal joint. The proximal row consists 

 of two large bones more or less closely united, and articulated 



* M. Fiirbringer, " Die Knochen u. Muskeln der Extremitdten bei den 

 Schlangendhnlichen Saurien," Leipzig, 1870. 



