24 NATURAL HISTORY. 



and turned until placed in a proper position for being swallowed, when it is eaten in the same 

 manner as food is taken by Lizards. The teeth are arranged in double rows, but are of unequal 

 size. The larger teeth are in the lower jaw. The stomach and liver are both large, and the pancreas 

 is in the usual position. The intestine has a rudimentary spiral valve. These fishes come to the 

 surface for air. They attain a length of upwards of five feet. In the Lepidosteus osseus the second 

 row of teeth in the upper jaw is found on the palatine bones in young specimens, but in the adult 

 only minute teeth are to be seen in this position. In the Lepidosteus viridis the teeth on the 

 palatine bone are larger, and similar to the strong teeth on the maxillary. The larger teeth have 

 their bases folded, somewhat after the pattern of the fossil Labyrinthodonts. Professor Cope includes 

 both the genera Amia and Lepidosteus with the Teleostean fishes. 



OBDER III. HOLOCEPHALA.* 



FAMILY. CHIMJERID^E. 



The Chimrera, which has sometimes been called the " King of the Herrings," is like Sharks in 

 having the nose projecting in front of the mouth, and resembles some Skates in the long tail, which 

 tapers like a whip. But it differs in wanting the openings for the gills which are visible in both 

 those groups ; not that they are absent in the Chimsera, but are concealed by a backward fold of 

 membrane like a rudimentary operculum, which extends in front of the pectoral fin. Under this 

 membrane, which gives a single external opening for the gills on each side, are four clefts in the 

 gill-cavity. There is another very important difference from the Sharks, in that the skull is 

 blended with the jaws. The skeleton is almost entirely formed of cartilage, and almost the only 

 bones in the body are those which form the jaws. The genus has hence been placed, together with 

 an allied genus, as a separate division of the cartilaginous fishes (Holocephala). Very little is known 

 of the habits of the C/timara monstrosa, for it comes to the surface only in the night, and is rare 

 in northern latitudes. It is often met with in the Polar Seas. Its ordinary food consists of 

 Crabs and Shell-fish, but it also travels in pursuit of Herrings and other migratory fishes. It is 

 also said to feed on Jelly-fish. The flesh is reported to be hard and coarse-eating. Oil has some- 

 times been obtained in Norway from its liver, and used for disorders of the eyes. The genus 

 is represented by three species, but the common Chimsera ranges round the shores of Europe, and 

 is not unfrequently caught on the Mediterranean coasts of France ; and it is met with at the Cape 

 of Good Hope and in Japanese waters. This species is hardly more than three feet long; the 



* oAo<?, entire, solid ; KC</>OA^, head. 



CHIMERA COLLIEI. 



