296 



r. H. EDGEWORTH. 



been independently acquired; thus tlie absence of levatores 

 arcuum brancliialium and method of formation of the 

 trapezius also occurs in Selachii. The morphology of the 

 cranial muscles is thus in favour of an Amphibian ancestry of 

 Mammals. In the attachment of the posterior digastric to 

 the hyoid bar, and not to the lower jaw, some Mammals 



Text-fig. 1*4. 



UinJp* nv<>.. ,Vn.. 



■tlru ti^t^Alv. 





^''^•qi^-x^ 



94. 



Text-figs. 94 and 95.— Rabbit, embryo 13 luni.; transverse sec- 

 tions through the mandibnlar segment. Text-fig. 94 is the 

 more anterior. 



present a more primitive feature than is found in any adult 

 Amphibia. A descent from a proto-ampliibian stock is thus 

 suggested. 



The ancestry of Sauropsida has been the subject of but 

 few speculations. Fiirbringer was of opinion that ''Die 

 strepto-stylen Pro-reptilia aber haben sich neben den strepto- 

 stylen Pro-mammalia auf tiefer stehenden streptostylen 



