MORPHOLOGY OF CRANIAL MUSCLKS IN SOME A^ERTEBRATES. 171 



into muscles, can be homologous with epithelial structures in 

 the body, which are the " Mutterboden fur den verschiedenen 

 Harnkanalchen " (Felix). Nor do the lateral plates of the 

 head appear to be homologous with the " Seitenplatten " (of 

 Felix) in the body, for this term denotes the epithelium 

 lining the coelom. 



The Aulage of the rectus externa s may be regarded as a 



Text-fig. 3. 



•1 "^v 



*^Mi.^i ITlu 



Scylliniii, embiyo 9 mm., transverse section. The line attacbed 

 to tlie mark * shows the point of junction of the Anlage of the 

 external rectus Avith the hyoid myotome. 



very early anterior prolongation of the upper end of the 

 hyoid myotome, 



Ziegler was of opinion that the eye-muscles gave no 

 evidence of the primary segmentation of the head, but attri- 

 buted the Anlage of the rectus externus to the mandibular 

 segment. 



The Anlage of the obliquus superior was regarded by van 

 Wijhe as the second myotome of the head. On the analogy 

 of the rectus externus it may be looked upon as simply a 

 forward projection of the upper end of the mandibular 



