.10 



CliORDATA 



and females deposit their reproductive products in the water at the same time. 

 Many species have brighter colors or develop pearl organs (p. 493), at the time 

 of oviposition. In rare instances the males care for the young (sticklebacks); 

 more noticeable are the conditions in the lophobranchs (sea horses and pipe 

 fish), where the males receive the eggs in a brood pouch on the ventral surface. 

 A metamorphosis is known only in the eel-like fishes, the larvae of which (Lepto- 

 cep/ialiis) are flat, transparent, with colorless blood, enormous tails, and extremely 

 small trunk. These larvas normally occur in the sea at the depth of some 

 hundred fathoms. The fresh-water eels go to the ocean for propagation. On 

 the other hand, many salt-water fish go to fresh water for reproduction. 



The classification of the fishes is yet in an unsettled state. Most European 

 writers recognize tlu six divisions below. American authorities separate the 

 Ostariophysi from the Physostomi, the Pediculati and Hemibranchii from the 

 Acanthopteri, and unite the Anacanthini and some of the Pharyngognathi with 

 the Acanthopteri and make a distinct group, Synentognathi, of the'others. The 

 characters on which these divisions are based are less convenient for the tyro 

 than those adopted here. 



Order I. Physostomi. 



The character to which this name refers is not readily seen without dissection, 

 the persistence of the duct of the swim bladder. This is, however, correlated 

 with the soft character of the fin rays (few exceptions) and the abdominal position 

 of the ventral fins. The Ostariophysi are remarkable in having a chain of bones 

 (Weberian apparatus, p. 503) connecting the swim bladder with the ear. More 

 than a third of the food fishes and nearly all of the fresh-water fishes belong here. 



The Ostariophysial families are SILURID.-E (1000 species), or cat-fish; 

 CYPRINID^E, or carp (1000 species); the suckers, CATOSTOMID^E. GYMNOTI', 

 electric eel of South America. The other families are true Physostomes. The 

 SALMONID^, trout and salmon (Salmo*) Oswerus* smelt; Coregonus* white 

 fish; CtuPEiD.*:, herring, shad; ANGUILLID.E, eels, ESOCID^:, pike and pickerel. 

 AiiBLYOPsnxE, blind fish of Mammoth Cave. 



Order II. Pharyngognathi. 



The inferior pharyngeal bones (i.e., the last rudimentary gill arch) fuse to 

 form a single bone. Some have spiny fins; LABRID.E, Ctenolabrus* the cunners 



FIG. 560. Ctenolabrus ccenilcus,* cunner (after Goode). 



'hese arc placed among the Acanthopteri by American authors. Others have 



These are the Synentognathi and include the EXOCCETHXE, 

 some flying hshes. 



