682 



COMPARATIVE ANATOMY 



Fig. 404. 



/, A and B. Diagram of a vertebra of a bony fish. A, caudal ; B, trunk ; C, 

 amphicoelous ; D, procoelous ; E, opisthocoelous ; F, amphiplatyan vertebrae. The 

 head is supposed to lie at the left, c, centrum or body of vertebra ; ch, notochord ; 

 h.a., haemal arch ; h.c., haemal canal ; h.s., haemal spine ; h.z., haemal zygapophysis 

 or articulating facet ; m.b., intermuscular bone ; n.a., neural arch ; n.c., neural canal ; 

 n.s., neural spine ; n.z., neural zygapophysis ; r, rib. 



//. Composition of vertebrae of Reptiles, illustrated by the first and second 

 cervical vertebrae. (1) Atlas (first cervical) and axis (second) vertebrae of 

 Crocodile. (2) Atlas and axis of Metriorhynchus, a Jurassic Crocodile. (3) 

 Analysis of the first two vervical vertebrae of a Crocodile. 2, second basiventral 

 complex or "intercentrum" continued upwards into the meniscus or intervertebral 

 pad. (4) Diagram of the fundamental composition of a Reptilian vertebra or 

 other amniotic, gastrocentrous vertebra. (5) The first three cervical vertebrae 

 of Sphenodon. (6) Trunk- vertebrae of Eryops, a Permian Proreptile, typically 

 temnospondylous. cp, articular facet of the capitulum of a rib. ( 7 ) The complete 



