MOEPHOLOGY OF CRANIAL MUSCLES IN SOME YERTEBKATES. 207 



Acipenser and Polypterus, pierces it in Lepidosteus, Amia, 

 and Salmo. 



The development is not yet known in Polypterus. In the 

 first stages, hitherto described, of Acipenser rnthenns 

 (Parker), Lepidosteus (Parker), and Salmo trntta (Stcihr), 

 the hyomandibula is stated to abnt against the anditor}^ 

 capsule. Rutherford^ states that in the brown trout a down- 

 growth of no great size, from the periotic capsule at the edge 



Text-fig. o-t. 



^oJl |>'i. o| qa 



oAA. nvJuTuL I 



o^A^ "noLnJl tjh 



•OCA. ku^ ^ / '^' 



Aniia, embryo 10 mm., transverse section. 



of the fenestra ovalis, joins with the symplecticum in front of 

 the Vllth nerve, and finally unites with the primitive hyo- 

 mandibula. 



In 8 mm. embryos of Acipenser the hyoid bar, in a pru- 

 cartilaginous condition and unsegmented, does not extend up 

 to the auditory capsule. The A'lltli nerve passes over the 

 upper end of the bar, and then downwards outside it (Text- 

 fig. 19). In 8^ mm, embryos the hyoid bar extends up towards 



The paper is as yet only pulilislied in abstract. 



