GENERAL BIOLOGY 



741 



This great contrast in the conditions of propagation is 

 obviously a very characteristic feature. At this point, however, 

 we encounter the same difficulty met with in discussing the 

 reproduction of the miniate plants and food animals of the ocean, 

 for we are ignorant as to how often these small fishes reproduce 

 their kind during the year. 



Figs. 531 and 532 represent the eggs of Scombresox and 

 Trackypterus, and show that oceanic eggs are not all small. 

 The large e^g of Trackypterus (2.8 mm. in diameter) was 

 captured at Station 52, south of the Azores, and plainly shows 

 that the large and remarkable Trachypteridse propagate in 



Fig. 530. 



A. Egg from the surface, Station 48. 



B. Ovarian egg of Cyclothone signata, Garm. 



C. Ovarian egg of Cyclothone niicrodon, Giinth. 



D. Ovarian egg of Gastrostofnus bairdii. Gill and Ryd. 



E. Egg of Gadus callarias, L. 



(All^fA.) 



entirely oceanic conditions. Judging from their appearance 

 they probably live at similar depths as Argyropelecus and the 

 Stomiatidse. 



During the whole of our Atlantic cruise we constantly Vertical dis- 

 captured young fish, in fact many thousands in all. According young°fi"h.^ 

 to their vertical distribution these young fish may be divided 

 into two groups. Fig. 533 shows that the majority of the 3604 

 young fishes examined were taken in the uppermost 150 metres 

 of the sea. Most of the young fishes taken in appliances used in 

 deeper water have, in all probability, been taken while hauling 

 in the gear, and nearly all the peculiar large leptocephali have 

 also been taken in the upper layer. But there is a certain 

 group of young fishes which show a maximum frequency about 



