j3 2 DEVELOPMENT OF FISHES 



The eggs of Myxinoids are probably deposited at a 

 single time ; at first extruded by pressure of the body 

 wall ; then drawn out string-like, one egg following 

 another, attached by hooked and thread-like processes 

 (Figs. 186^4, 187 A). Little is known, however, of the 

 actual breeding habits of Myxinoids, either as to locality, 

 mode, or season ; individuals of Myxine and Bdellostoma 

 with ripe spawn have never been taken even in the 

 most favourable regions. It is supposed that their spawn- 

 ing does not occur in the immediate neighbourhood of 

 the shore, since detached eggs have been dredged in the 

 deeper water. Their breeding time is probably in the 

 early spring, although possibly intermittent spawning 

 takes place. In Myxine, according to Putnam,* the bulk 

 of the eggs may be deposited as late as the beginning of 

 winter. 



The spawning habits of Petromyzon, on the other hand, 

 have been especially favourable for observation. The eggs 

 are deposited in shallow and clear water and the move- 

 ments of the fish may readily be followed. In the small 

 stream at Princeton,! for example, the lampreys make their 

 appearance about the middle of May and remain on the 

 spawning grounds two or three weeks. Their "nests" 

 are seen scattered thickly on the gravelly shoals, often but 

 a few feet apart. Each will be occupied by several males 

 and a single female, the latter conspicuous on account of 

 greater size. When spawning, the lampreys press together 

 and cause a flurry in the water at the moment when the 

 eggs and milt are emitted. This portion of eggs will now 



* As observed at Grand Menan. Pro. Bost. Soc. Nat. Hist. Feb. '74. 



t Professor McClure and Dr. O. S. Strong have here repeatedly observed 

 the spawning lampreys; it is to their account that the writer is here indebted. 

 Compare, also, the excellent account given recently by Professor Gage. 

 Ref. p. 234. 



