214 



THE 1'Roo. 



which corresponds with the scapular portion of the pectoral 

 girdle, ossifies as the ilium ; in the part below the acetabulum, 

 the anterior or pubic portion remains cartilaginous, while the 

 posterior portion ossifies as the ischium. 



The pelvic girdle is, in its early stages, and until shortly 



FIG. 96. The skeleton of the Frog, seen from the dorsal surface.' The left 

 supra-scapula and scapula have been removed. 



, astragalus, c, calcaftovmi. d, supra-scapula. e, exoccipital. /, femur, fp, fronto- 

 parietal. g, metacarpals. h, Immerus. i, ilium. , nietatarsals. 7, caryms. m. msixillii.. 

 11, nasal, o, pro-otic, p, ptery.u'oid. pm, prcmaxilla. </, quadrate- jugal. r, radio-ulna. 

 *, squamosal. se, sphen-ethmoid. ,vr, sacral vcrtchni. /, tibio-fibula. it. urostylc. 



before the metamorphosis, about the same length as the pectoral 

 girdle ; and, like this, lies at right angles to the vertebral 

 column. As the hind limbs lengthen, during and after the 

 metamorphosis, the ventral or acetabular end of the girdle moves 

 backwards, so that the ilium, which lengthens considerably at 



