SKELETON. 69 



As separate cartilages there are appended to the skull a 

 suspensoriiim, a palatine, mandible, hyoid, and rudimentary 

 maxillary elements. 



The suspensorium is movably attached to the side of the 

 skull. It generally consists of one piece only, but in some 

 Eays of two. In the Eays it is articidated with the mandible 

 only, their hyoid possessing a distinct point of attachment to 

 the skull. In the Sharks the hyoid is suspended from the 

 lower end of the suspensorium together with the mandible. 



Wliat is generally called the upper jaw of a Shark is, as 

 Cuvier has already stated, not the maxillary, but palatine. 

 It consists of two simple lateral halves, each of which articu- 

 lates with the corresponding half of the lower jaw, which is 

 formed by the simple representative of Meckel's cartilage. 



Some cartilages of various sizes are generally developed 

 on each side of the palatine, and one on each side of the 

 mandible. They are called labial cartilages, and seem to 

 represent maxillary elements. 



The hyoid consists generally of a pair of long and strong 

 lateral pieces, and a single mesial piece. From the former 

 cartilaginous filaments (representing brancliiostegals) pass 

 directly outwards. Branchial arches, varying in number, 

 and similar to the hyoid, succeed it. They are suspended 

 from the side of the foremost part of the spinous column, and, 

 like the hyoid, bear a number of filaments. 



The vertical fins are supported by interneural and inter- 

 haemal cartilages, each of which consists of two and more 

 pieces, and to which the fin-rays are attached without articu- 

 lation. 



The scapular arch of the Sharks is formed by a single 

 coracoid cartilage bent from the dorsal region downwards and 

 forwards. In some genera (Scyllium, Squaiina) a small sepa- 

 rate scapular cartilage is attached to the dorsal extremities 

 of the coracoid; but in none of the Elasmobranchs is the 



