MOEPHOLOGY OF CKAXIAL MUSCLES IX SOIME VEETEBRATES. 187 



The intermandibularis of Teleostomau embryos forms, at 

 first, with its fellow, a transverse muscle attached laterally to 

 Meckel's cartilage (Text-figs. 23, 24, 28). 



In Salmo it does not extend backwards, but does so in 

 Acipenser, Lepidosteus, Amia and Polypterus, and partially 

 underlies the fore part of the interhyoideus. In Salmo, 

 Polypterus,^ and Lepidosteus, it remains single, in Acipenser 

 and Amia it divides into anterior and posterior parts. In 



Text-fig. 16. 



votjA.itv ftr. 



n«x* iu^ 



a<)ux.nuxruL 



CO*V.ITUVrv<i , 



Scyllium, embryo 30 mm., trausverse section. 



Acipenser the intermandibularis anterior (Csg of Vetter) is 

 attached laterally to Meckel's cartilage, and the intermandi- 

 bularis posterior (Cs^ and Cso of Vetter) spi-eads upwards, 

 laterally, towards the skull. ^ In Amia both intermandi- 

 bularis anterior'^ and posterior^ are attached laterally to 



' Intermaxillaris anterior of Pollard. 



" All these parts are innei-vated by the Ttli (Allis). 



^ Intermandibularis of Allis. 



^ Superficial or inferior portion of geniohyoid of Allis ; the muscle Las, 

 however, no genetic relation to the superior portion of the geniohyoid 

 (called in this paper " hyomaxillaris ") which is developed in the hyoid 

 segment. 



