MORPHOLOCIY (»F CIIAXIAL MUSCLES IN SOME VEUTEIUIA'l'ES. 209 



the auditory capsule aud in front of, and outside, the Vllth 

 nerve, which now winds round it (Text-figs. 20 and 21). The 

 hyo-inandibular cartilage is formed in part from the upper 

 portion of the bar present in 8 mm. embryos, and in part 

 from the upward extension. The hyoid muscles in 8 mm. 

 embryos consist of a hyoid mj'otome, the anterior part of 

 which is inserted into the upper end of the hyoid bar (Text- 



Text-fig. 37. 



fig. 19), forming a levator hyoidei, and the posterior part of 

 which forms a dorso-ventral sheet — homologous with C^,vd of 

 Selachians — continuous ^vith the posterior part of the inter- 

 hyoideus (Text-fig. 21), whilst the anterior part of the inter- 

 hyoideus is inserted laterally into the hyoid bar. 



The sequence of events in the other Teleostomi examined 

 is similar to that occurring in Acipenser, the upgrowth of 

 the hyoid bar to the auditory capsule taking place in 8 mm. 

 embryos of Lepidosteus, G^ mm. embryos of Aniia, and 5,V mm. 

 embryos of Sal mo fario. In no case was any downgrowth 



