364 TROPICAL AND SOUTHERN FISHES 



adult female captured at Port Royal, Jamaica, in the year 1824, measuring no less 

 than five feet across the fins, and weighing about twenty pounds. Such a large 

 fish is quite capable of taking care of itself from the time it makes its appearance 

 in the world ; and this is doubtless the reason for the production of only a single 

 offspring at each birth. In the case of egg-laying fishes of small size, where no 

 care is taken of the spawn, an immense number of eggs is necessary to ensure the 

 normal number of individuals, but in the case of viviparous fishes a single young 

 one at a time is sufficient to maintain the species at its ordinary level. As a rare 

 abnormality a devil-fish may, however, give birth to twins, although fivrther in- 

 formation on this point is desirable. It has also been stated that a devil-fish taken 

 in the Seychelles was found to be full of eggs. This seems to indicate that these 

 fishes produce a number of eggs, one of which alone undergoes development. 

 Another curious statement is to the effect that a wounded female devil-fish which 

 gave birth to a living offspring was found on dissection to possess a mammary 



A STINO-RAY. 



organ which discharged as much as a pailful of milk. This statement admits of a 

 satisfactory explanation as the result of modern investigations, for it has been 

 found that the mucous membrane of the oviduct of the sting-rays secretes a milk- 

 like fluid during the period of pregnancy, which is squeezed out by special 

 muscular arrangements and absorbed by the foetus by way of the modified first 

 pair of gill-clefts or spiracles ; the other gill-clefts being closed at the time. A 

 similar arrangement for the nutrition of the embryo doubtless obtains in the 

 devil-fishes; and the aforesaid statement, which dates from the year 1823, is thus 

 explained. Although the nutritive fluid secreted by the female fish and ingested 

 by the young has considerable resemblance to milk, yet it is chemically different ; 

 and as it is absorbed through the head spiracles instead of being taken in by the 

 mouth, it cannot be said that rays suckle their young. 



Some of the smaller rays produce quite a number of young at a birth, and in 

 certain instances these differ remarkably in colouring from their parents. An 

 electric ray {Narcine brasiliensis) taken some years ago off the coast of Florida gave 



