256 F. H. EDGEWOin'H. 



But ill the second, third, and fourth branchial segments 

 of Auuran tadpoles, the fourth of Necturus and Triton, the 

 second, third, and fifth of Ceratodus, and in those segments 

 of Teleostomi in which h^^pobranchial cranial muscles are 

 formed, the lower ends of the branchial myotomes also grow 

 downwards and inwards above the ce])halic coelom, towards, 

 or to the middle line forming the (lateral halves of the) 

 transversi ventrales, or their homologues, the lower portions 

 of the obliqui ventrales. In branchial segments of Teleostomi, 

 where hypobranchial cranial muscles are not formed, i.e. 

 first four of Lepidosteus, first three of Amia and Salmo, 

 fourth of Acipenser, there is a similar downward and inward 

 growth of the ventral ends of the branchial myotomes, to 

 form tlie lower portions of the obliqui ventrales. 



The hinder part of the transversus ventralis 1\ of l^olyp- 

 terus and Amphibia, and of the transversus ventralis V 

 of Ceratodus, conies into intimate relations with the ventral 

 larynx, though in varying ways, underlying it in Amphibia 

 and Ceratodus, forming a dilatator in Polypterus. 



The portions of the branchial inj'otomes next above the 

 Anlagen of the hypobranchial cranial muscles form the 

 Anlagen of the muscles of the external gills in the first 

 three segments of Necturus and Triton, and the Mm. mar- 

 ginales in the first three segments of Annran larvie and the 

 first four segments of Ceratodus. Homologous Anlagen form 

 the upper portions of the obli(pii ventrales in Teleostoman 

 embryos — of the first four segments of Acipenser, Lepi- 

 dosteus, Atnia, Salmo, Polypterus (Pollard), and of the third 

 and fourth segments of Polypterus senegalus ; these may 

 or may not unite with the lower portions. In some segments 

 of Teleostomi, i.e. first three of Acipensei, fourth of Lepi- 

 dosteus, Amia, and 8almo, adductors are formed from por- 

 tions of the myotomes lying internal to the branchial bars; 

 they are not developed in Polypterus. 



In Scyllium the portions of the branchial myotonies next 

 above the Anlagen of the coraco-branchiales form adductors 

 internal to the branchial bars, and the superficial con- 



