70 ON THE ORISSA COAST 



of species in which the females are deh'berately courted 

 by, and deHberately make a choice of, the males. 

 Numerous writers besides Darwin have discussed this 

 aspect of piscine life, but I may mention here three 

 species of Orissa fiat-fishes in which we may suppose 

 that such a courtship takes place. They are Arno- 

 glossus macro lop hus and Brachypletira xanthosticta, in 

 both of which the anterior rays of the dorsal fin form 

 a fine erectile, plume-like crest, of which the female 

 has no trace, and Rhomb oidichthys azuretis, in which 

 the male alone has its forehead adorned on one side 

 with azure blue spots, which gleam like jewels. 



But what took the most complete hold of my 

 attention, when working on the Orissa fishes, was the 

 discovery that certain sting-rays (fishes closely related 

 to the sharks and skates) nourish their unborn young 

 on a secretion analogous to milk. Everyone, of course, 

 knows that in the sub-class to which the sharks and 

 rays belong, the females either give birth to living 

 young, or else lay large eggs which, like those of 

 birds and reptiles, are impregnated before they are 

 laid, and are enclosed in a shell. It is well known, 

 moreover, that, wh-ere the young are born alive, some 

 species are born with a structure analogous to an 

 ''after-birth" attached to them, and some species 

 have no trace of any such structure. The ''after- 



It is, of course, known to serious students of zoology, that the 

 placenta of the sharks is formed entirely by the overgrown yolk-sac. 



