S04 



FISHES 



CHAP. XVIII 



higher, for the purpose of spawning, each female being attended 

 b)^ from one to four males."' During brief recurring periods of 

 excitement, accompanied by convulsive lashing movements, the 

 eggs and sperm are emitted. The eggs are extremely sticky, and 

 adhere tenaciously to the rocks and stones on which they are 

 deposited. In a few days the embryos hatch out, and at this 

 stage the larva has a huge mouth surmounted by a terminal 

 preoral disc, fringed witli a row of marginal wart-like suckers 

 (Fig. 300). The yolk sac is so large as greatly to hamper the 

 movements of the larva ; hence, by means of its suckers, the young 

 Lejndosteus attaches itself to surrounding objects, and remains 



Fig. 300. — Larval Lepidosteus osseus, 11 mm. long, a, Anus ; u.f, c.f, d.f, developing 

 anal, caudal, and dorsal fins ; m, mouth ; ol, olfactory organ ; o^j, operculum ; 

 pt.f, pectoral fin ; s, sucker. (From Balfour and N. Parker.) 



almost entirely motionless for some little time after hatching. 

 Later, about a fortnight after escaping from the egg, the yolk 

 becomes completely absorbed, the suckers degenerate and eventually 

 disappear, and the larva, freed from its load of nutritive reserve, 

 assumes a more active life. After the absorption of the yolk the 

 larvae of Mosquitos appears to form the exclusive diet of the 

 young Lepiclosteus for some time, but very soon young Fishes are 

 readily devoured.^ 



Lepidosteus seems to have been abundant in Europe during 

 the Eocene and Miocene periods, but became extinct before the 

 Pliocene. In North America, also, the genus dates from the 

 Eocene, and still survives. 



Order IV. Teleostei. 



[For the account of this Order, see pp. 541 f ] 



^ Alex. Agassiz, Proc. Amer. Acad. Arts and Sc. xiii. 1878, p. 65 ; Mark, Bull. 

 Mas. Comp. Zool. Harvard, xix. 1890, p. 1. 

 ^ Mark, op, cit. p. 3. 



