OSSEOUS SYSTEM. 191 



and upon the superior maxilla, and may be probably compared 

 with the labial cartilages of the Plagiostomi. Other bones, how- 

 ever, besides this occur in many of the Osseous Fish, which are still 

 more analogous to the system of labial cartilages in the Sharks. 

 Thus a cartilage is frequently found in the fold of the angle of the 

 mouth, which in Sciaena aquila is of very large size ; it is mostly 

 conical in form, attached by its basis to the lower jaw, and by the 

 other end, which is free, to a fold of the mucous membrane. It is 

 much more rare for a similar cartilage to exist in the upper jaw, as, 

 for example, the two fine strips of cartilage in Dactyloptera volitans, 

 where they correspond completely with similar structures in the 

 Sharks. 



The vomer is attached posteriorly to the anterior extremity of 

 the sphenoid bone, and lies beneath the ethmoid. It very frequently 

 supports teeth, but in the Carp projects into a couple of rounded 

 nodules. The palatal bones are situated in front of and to the sides 

 of the ethmoid, and in the direction backward they abut against 

 the pterygoid bones. Each palatal bone is united to the vomer by 

 means of a joint, and by means of this the mobility of the bony 

 apparatus that rests upon the articulating or quadratal portion of 

 the temporal is effected. Occasionally, e. g. in Muraena, Muraeno- 

 phis, the palatal and pterygoid bones concur to form a single bone, 

 which is very large in Gymnotus. The nasal bones are usually 

 situated, as a pair of elongated flat bones, in front of and upon the 

 ethmoid, e. g. in the Pike. In the Carp, an elongated, stile-shaped 

 bone occupies their place ; it is somewhat dilated at each end, and 

 upon its sides there is always found a smaller discoidal bone. In 

 Fish of the Eel kind, the nasal bones, or their analogues, are com- 

 pletely absent. Externally, upon the lower edge of the orbitar 

 cavity in many Fishes, there is situated a series of flat bony scales, 

 frequently five in number, which are much developed in the Carp, 

 and the most anterior of which is the largest. They are called 

 infra-orbital bones, and, from their forming a kind of arch, may be 

 compared to the jugal bone. This chain of ossicles is subject to 

 much variety, being wanting in Muraena, Muraenophis, Balistes, and 

 other anomalous Fishes, while occasionally six bony scales occur, as 

 in Perca, where they are very small, or they are only four in num- 

 ber, as in Trigla, and of remarkably large size ; in some cases only 

 two or one exist. There is occasionally found upon the border of 

 the orbit, and situated upon the frontal bone, a peculiar bone of 

 small size, the superciliary ; examples of it are furnished by Cypri- 



