— 111 — 



this tendon, AoAg-A^jj, a ligamentous band runs backward and is inserted on the internal surface 

 of the quadrate. 



The levator arcus palatini runs downward internal to Aj and then internal to A,, lying always 

 external to A3 and also always external to the palato-quadrate. The course of the muscle is thus 

 in accord with the conclusion, already stated, that the dorsal portion of the hind edge of metapterygoid 

 of Cottus represents the inner one of the two flanges on the hind edge of the metapterygoid of 

 Scorpaena. 



The dilatator operculi arises partly in the dilatator fossa, but mainly on the external surface 

 of the dorsal end of the hyomandibular and on adjacent portions of the preopercular, and is inserted 

 .on the opercular as in Scorpaena. 



The adductor hyomandibularis, and adductor and levator operculi are as in Scorpaena, but 

 the latter muscle is represented by several separate bundles of muscle fibers all of which extend from 

 the dorso-lateral edge of the skull to the dorsal edge of the opercular or subopercular; the posterior 

 bundles being delicate bands lying in the membrane that closes the dorsal end of the opercular 

 opening. 



5. LATERO-SENSORY CANALS. 



The main infraorbital canal of Cottus traverses the four infraorbital bones without Inter- 

 ruption, and then enters and traverses the postfrontal, at the dorsal end of which it anastomoses 

 with the penultimate tube of the supraorbital canal. It then turns sharply backward and traverses 

 in succession the pterotic, lateral extrascapular, suprascapular and supraclavicular. The lachrymal 

 lodges two sense organs of the line; the first suborbital bone lodges two regulär organs and, in the 

 one specimen examined, what was apparently a much smaller and additional organ between the 

 two regulär organs; the second suborbital bone lodges two organs; and the postorbital bone one 

 organ: all of these organs being innervated by branches of the buccalis lateralis. The number of organs 

 in this part of the line, excepting the small and apparently supplemental organ in the first suborbital, 

 is thus exactly the same as in Scorpaena, but the third latero-sensory ossicle has, in Cottus, fused 

 with the fourth ossicle and so forms part of the first suborbital bone instead of fusing with the first 

 and second ossicles to form part of the lachrymal. 



The postfrontal lodges one organ, innervated by a brauch of the oticus lateralis; the pterotic 

 two organs, one innervated by the oticus lateralis and the other by a brauch of the supratemporalis 

 lateralis vagi; the lateral extrascapular and suprascapular one organ each, innervated by branches 

 of the supratemporalis lateralis vagi; and the supraclavicular one organ, innervated by the first 

 brauch of the lateralis vagi. This part of the line thus differs from that in Scorpaena only in that 

 the pterotic lodges an organ innervated by the lateralis vagi; the dermal component of that bone 

 thus being formed by the fusion of two latero-sensory ossicles. 



The supratemporal commissure lodges two sense organs on either side, one lying in the lateral 

 extrascapular and the other in the parieto-extrascapular, both innervated by brafiches of the supra- 

 temporalis lateralis vagi. 



The supraorbital canal traverses the nasal and frontal bones, and anastomoses by its penulti- 

 mate primary tube with that infraorbital tube that lies between the postfrontal and pterotic bones. 

 The canal contains six sense organs, one lying in the nasal and five in the frontal, all innervated by 

 branches of the ophthalmicus lateralis. A primary tube leaves the canal between each two adjoining 



