223 



CARTILAGINOUS FISHES. 



Feom the peculiar structure of the skeleton, these form an 

 interesting group, holding a place between the Cuttle-fish, in 

 which there is but the rudiment of a skeleton, and the osseous 

 fishes, in which the vertebrated structure in this class of ani- 

 mals reaches its full development. Among them there is 

 great diversity. One little fish, of rare occurrence, the Lance- 

 let {Amphioxus lanceolatus), which is not much more than 

 an inch in length, has no skeleton, properly so called, but 

 merely a membranous thread ; in the Lamprey the divisions of 

 the vertebrie are marked, so that they resemble beads placed 

 on a string ; in the Shark and the Sturgeon, the divisions of 

 the vertebrse are complete. 



Peteomyzid^.* — The family of the Lampreys {Fig. 194) 



Fig. 194.— RivKR Lamprkv. 



comprises the Lancelet, the fish just mentioned. Some of 

 them dredged up in deep water, off the southern coasts of 

 England, by ^Ir. MacAndrew, were exhibited by Professor 

 Edward Forbes at the Southampton meeting of the British 

 Association, September, 1846. They have, ere now, been 

 ranked with the MoUusca, and exhibit pecuharities of a nature 

 so remarkable as to be objects of the highest interest to the 



* That is, the family of the " Stone-suckers," an appellation bestowed 

 on them because, by means of their circular mouths, they can adhere to 

 stones. Like other terms, it is derived from two Greek words. 



