THE GANOIDEl. 



123 



beak, wbich, in Spatularia, is very long, flattened, and spatu- 

 late. In the perichondium of the base of the skull, median 

 bones, answering to the vomer and to the parasphenoid of 

 Teieostean fishes, are developed ; and, in that of its roof, ossi- 

 fications, which represent the parietals, frontals, and other 

 membrane bones of the Teleostei, appear. 



The framework of the jaws in Spatularia is verj' similar 

 to that in the jElasmobranchii. There is a partly cartilagi- 

 nous, and partly ossified, suspensorial cartilage {A, JB, Fig. 39), 

 which gives attachment below, directly, to the hyoidean arch 

 (Sy), and, indirectly, to the jaws. The latter consist of a 



All /« 



Fig. 89.— Side-view of the skull of /SpaiM^oWo, with the beak cut away, and the autenor 

 (asc\ and posterior ( psc), semicircular canals exposed : Au, auditory chamber ; Or, 

 the orbit with the eye ; N, the nasal sac ; Hy, the hyoidean apparatus ; Br, the repre- 

 sentatives of Jhe branchiostegal rays ; Op, operculum ; Mn, mandibk ; A, B, suspenso- 

 rium; D, palflto-quadrato cartilage; E, maxilla. 



palato-quadrate cartilage {D) united by ligament with its fel- 

 low, and with the prefrontal region of the skull at F. ; and 

 presenting, at its posterior end, a convex articular head to the 

 cartilage of the mandible, or Meckelian cartilage, Mn. It is 

 obvious that A, JB, corresponds with the hyomandibular, or 

 suspensorial, cartilage in the Sharks and Rays ; D, with the 

 palato-quadrate cartilage, or so-called " upper jaw," and the 

 cartilage of the mandible with the lower jaw in these animals. 

 But, in the Ganoid fish, an osseous operculum ( Op) is attached 

 to the hyomandibular ; and a branchiostegal ray {Br) to the 

 more strictly hyoidean part of the skeleton of the second vis- 

 ceral arch; while a membrane bone {E) representing the 

 maxilla, and another {Mn,) the dentary, of the lower jaw ia 

 Teleostei, are developed in connection with the palato-o;aadrate 

 and mandibular cartilages. 



