264 NATURAL SCIENCE. Oct., 



shown. Molge watlii is chosen to illustrate the opisthoccelous 

 vertebrae of the Salamandridae, and as examples of amphicoelous 

 vertebrae those of Menopoma and Siren are exhibited. The amphi- 

 coelous character of the vertebrae of the Apoda and the two-headed 

 nature of the ribs are shown by selected vertebrae of Ichthyophis. 

 ' The vertebrae of Labyrinthodontia may be fully ossified and amphi- 

 ccelous, or may consist of a neural arch and a ring-like centrum and 

 intercentrum (such emholomerons vertebrae occur chiefly in the caudal 

 region), or may be composed of a neural arch, a pair of pleurocentra, 

 and an intercentrum [rachitomous type, found mostly in the trunk 

 region).' Drawings of restored vertebrae of Loxomma and Eryops 

 illustrate these two types. 



Pectoral Girdle. — * In the Anura there is a coracoidal fene- 

 stration between the precoracoid, the epicoracoid and the coracoid. 

 The epicoracoid cartilages overlap in the Avcifera, but fuse in the 

 ventral median line in the Firmisternia. Closely applied to the pre- 

 coracoid cartilage is a membrane bone, the clavicle.' ' In the 

 Urodela a scapula, a coracoid and a precoracoid can be distinguished. 

 The coracoids overlap in the ventral median line and the sternum is 

 unossified.' ' In the Labyrinthodontia there is a dermal thoracic 

 buckler composed of a median plate (interclavicle) and two lateral 

 plates (clavicles). The pectoral girdle proper is probably largely 

 cartilaginous.' The examples furnished are, for Anura, Rana, Bufo, 

 Discoglossus, Callula, and Xenopus ; for Urodela, Salamandva and Meno- 

 poma ; and for the Labyrinthodontia, a drawing of a partly-restored 

 pectoral girdle oi Actinodon. 



Pelvic Girdle. — ' In the Anura the ilia are greatly elongated and 

 backwardly rotated. The pubes are usually unossified. As in other 

 Amphibia there is no obturator foramen.' ' In the Urodela the ilia 

 are set at right angles to the vertebral column ; the pubes are usually 

 cartilaginous and there is an epipubic cartilage.' ' In the Labyrintho- 

 dontia the ilium is vertical as in Urodela. The pubis is ossified but 

 does not enter into the formation of the acetabulum.' As illustra- 

 tions are given, Rana as representing the Anura, Salamandva and 

 Menopoma as examples of the higher and lower Urodela, and a 

 drawing of a restored pelvis of Mastodonsatims to represent the 

 Labyrinthodontia. 



Limb Skeleton. — ' In the forelimb of Anura the radius and 

 ulna are fused, the pollex is rudimentary, there are two centralia in 

 the carpus, and the intermedium and carpale 5 are absent.' Examples : 

 Rana guppyi, Discoglossus, and Rhacophorus, the latter to show the so- 

 called supernumerary phalanx. ' The hind-limb of Anura is elon- 

 gated and modified for leaping or swimming. The tibia and fibula 

 are fused, the astragalus and calcaneum are elongated, and the inter- 

 medium and tarsalia 4 and 5 are absent. There is a prehallux of two 

 or more segments.' Example : Rana guppyi. 



' In the majority of Urodela the fore-limb is tetra- and the hind- 



