516 



F. H. EDGEWORTH. 



the ceratoliyal disappears/ and the lower end forms a short 

 cornu to the cart, entoglossa, which is, therefore, a median 

 basihyal or glossohyal with ceratoliyal cornua. The middle 

 piece (Copula i, of Gaupp) is a first basibranchial, and the 

 urohyal (Copula ii) a second basibranchial.^ 



This conclusion is supported by comparison with the condi- 

 tions found in Reptiles. In Spheuodon, Lacertilia vera, 

 Rhiptoglossa, Chelonia, and Crocodilia there is a continuous 

 basihyobranchial cartilage, and in the first four groups there 

 are ceratohyal cornua homologous with those in Gallus. In 



0. sup. an 



mand my 



Text-fig. 8. — Sagittal section through an emhryo of Gallus, with 

 4 gill-pouches. (For explanation of lettering see p. 555.) 



Sphenodon these ceratohyal cornua are formed by ceratohyal 

 bars which are continuous above with the hyomandibulars, 

 in Agama, Chamgeleon, and Chelone they are the lower ends 

 of ceratohyal bars which, in embryonic stages, were continuous 

 with the hyomandibulars. In the Crocodilia there are no 

 ceratohyal cornua to the basihyobranchial, and the single 



' The small bit of cartilage whicli is described by Geoffrey Smith as 

 separating from the lower end of the infrastapedial on the eightli day is 

 probably homologous with that called "stylohyal" by Parker in Ohelidon 

 u r b i c a. 



