THE GANOIDEI. 



123 



beak, wliicli, 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 very 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 

 (S-l/), and, indirectly, to the jaws. The latter consist of a 



All Ji&c 



Or fjar, '_,-<^5= 



Fig. 39. — Side-view of the skull of ^Spa^w^flrfai-wifh the beak cut away, and the anterior 

 (fisc)^ and posterior ( psc\ semicircular canals exposed : A%i,^ auditory chamber ; Or^ 

 the orbit with the ej^e ; N, the nasal sac ; i/y, the hyoidean apparatus ; JSr, the repre- 

 sentatives of the branchiostegal rays ; 6>j9, operculum ; j)/n, mandible ; A^ B^ suspenso- 

 rium; i>, palato-quadrate cartilage; E^ maxilla. 



palato-quadrate cartilage (7)) 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 ( O}!) is attached 

 to the hyomandibular ; and a branchiostegal ray {J3r) to the 

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

 ceral arch ; while a membrane bone (JE) representing tha 

 maxilla, and another {3In) the dentary, of the lower jaw in 

 Teleostei, are developed in connection with the palato-quadrate 

 and mandibular cartilages. 



