EVOLUTION OF DEVIL-FISH. 81 



(Pteroplatcea micrura) and its embryo. He says : The 

 little embryo also revealed some secrets of its own 

 genealogy. It was shaped, not like a skate, but more like 

 a shark, having a shark's snout and a shark's tail : like a 

 shark also, it had its gill clefts placed on either side of its 

 head (italics ours — compare with photograph and remarks 

 made about situation of gill-clefts in devil-fish), and not 

 on the under-surface of its body as they are in all skates 

 and rays. Unlike those of most sharks, however, were 

 its pectoral fins ; for these, instead of standing out at 

 right angles to the body, were produced to form a pair 

 of flaps running forward with a slight twist, one on either 

 side of the head." 



" Could we have seen the embryo at a later stage, we 

 should have found that these two flaps had fused with the 

 head, so as to push the gill clefts down to the under-surface, 

 and to produce the broad disc-like body characteristic 

 of the skates and rays. There are some rays, such as the 

 devil-fish (Dicerobatis and Ceratophera), in which the flap- 

 like anterior prolongations of the pectoral fins are not 

 entirely fused with the head, but stand out in front of it 

 like a pair of horns ; these, judging from the form of the 

 embryo of Pteroplatcea micrura, may perhaps be regarded 

 as * unfinished ' rays." 



Thus in these few lines we get a gHmpse of the mode 

 of origin of the curious horn-like fins seen in the devil-fish ; 

 of how its gill clefts came to be where they are now, 

 viz., on the under-surface of its body, instead of on the 

 side of its head as in the sharks ; and of the natural 

 affinity which it has to the shark tribe generally. 



Why these devil-fish, as well as other rays, should pro- 

 duce young in such an unfish-like manner is a question 

 which would be too difficult for us to answer. Only one 

 baby devil-fish is bom as the general rule, but twins 

 have been recorded. From the moment of birth they 

 are quite capable of looking after themselves, in which, 

 of course, they differ from mammals, whose young have 

 to be suckled. 



F 



