510 



CHORD ATx\ 



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

 INIanv species ha\e brighter colors or develop pearl organs (p. 493), at the time 

 of o\"iposition. In rare instances the males care for the young (sticklebacks); 

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

 fisli), where the males recei\e the eggs in a brood pouch on the ventral surface. 

 A metamorphosis is known only in the eel-like fishes, the larvx of which (Lcpto- 

 ceplialiis) are fiat, transparent, witli colorless blood, enormous tails, and extremely 

 small trunk. These larv;e 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. jNIost European 

 writers recognize the six divisions below, .\merican authorities separate the 

 Ostariophvsi from the Physostomi, the Pediculati and Hemibranchii from the 

 .A.canthopteri, and unite the .\nacanthini and sorne of the Pharyngognathi with 

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

 characters on which these dl^^slons are basecl 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. iNIore 

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



The Ostariophysial families are Silurid.e (iooo species), or cat-fish; 

 Cyprinid.e, or carp (1000 species); the suckers, C.\tostomid.e. Gymnoti, 

 electric eel of South .\nierica. The other families are true Phvsostomes. The 

 S.-VLSIONID.E, trout and salmon (Sabno*) Osnicrus* smelt; Corcgoiius,''' white 

 fish; Clupeid.e, herring, shad; Axguillid.e, eels, Esocid.e, pike and pickerel. 

 AiiBLYOPSiDJi, 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; L.\brid.e, Clciiolabriis,* the cunners 



/iy^Ay^y^^^ 



Fig. 5O0. — CleiuiUibnis ctrnilciis* cunncr (after Goodc). 



These are placed among the .\canthopteri by American authors. Others have 

 only soft fin rays. These are the Synentognathi and include the ExocarriD.E, 

 some flving fishes. 



