512 



F. H. EDGEWORTH. 



The treatises of Gadow and Hoifuian liave been taken as 

 guides for the adult anatomy of the head-muscles of the 

 Sauropsida. Some changes in the nomenclature have been 

 made in an attempt to apply identical names to homologous 

 muscles, for examination of their development shows that 

 different names have been given to homologous muscles/ and 

 the same name to muscles of different origins and morpho- 

 logy .^ A list of the terms employed is given in an appendix. 



Visceral Cartilages. 



The development of the visceral cartilages in the various 

 groups of the Sauropsida has already been described by 



rped pi 



C-) ^- spl meso 

 ient.ceph cal 



Text-fig. 1. — Transverse section through embryo of Gallus, with 

 11 trunk somites. (For explanation of lettering see p. 555.) 



Parker, Howes and Swinnertou, and by Broom ; and I have 

 very little to add. An interesting point is, that ^in early 

 stages of Tropidonotus there is a long pterygoid process pro- 

 jecting forwards from the upper end of the quadrate (text-fig. 

 37, p. 543). By the time chondrification has taken place this 

 pterygoid process has atrophied, and there is only its proximal 



' E. g. the anterior part of the ventral longitudinal muscles has been 

 called "cerato-mandibularis" (Sphenodon and Laccrtilia vera), "genio- 

 hyoid" (Chelonia and Rhiptoglossa), " maxillo-hyoideus" (Opliidiu), and 

 " anterior belly of maxillo-coracoideus " (Crocodilia). 



^ E. g. the name " cerato-hyoideus " has been given to a muscle developed 

 from the first branchial myotome of Sphenodon and Lacertilia vera, to 

 the hyoglossus in Crocodilia and Ehiptoglossa, and to a muscle developed 

 from the posterior mylohyoid in Birds. 



