Scientific Intelligence. — -Zoology. 197 



head emitted a vivid and greenish phosphorescent gleam, imparting 

 to the creature, by its own light, a truly ghastly and terrific ap- 

 pearance. The luminous eflFect was constant, and not perceptibly 

 increased by agitation or friction. I thought at one time that it 

 shone brighter when the fish struggled, but I was not satisfied that 

 such was the fact. When the shark expired, (which was not until 

 it had been out of the water more than three hours), the luminous 

 appearance faded entirely from the abdomen, and more gradually 

 from other parts ; lingering the longest around the jaws and on the 

 fins. The only part of the under surface of the animal which was 

 free from luminosity was the black collar around the throat ; and 

 while the inferior surface of the pectoral, anal, and caudal fins 

 shone with splendour, their superior surface (including the upper 

 lobe of the tail-fin) was in darkness, as also were the dorsal fins, and 

 the back and summit of the head. I am inclined to believe, that the 

 luminous power of this shark resides in a peculiar secretion from 

 the skin. It was my first impression that the fish had accidentally 

 contracted some phosphorescent matter from the sea, or from the 

 net in which it was captured ; but the most rigid investigation did 

 not confirm this suspicion, while the uniformity with which the lu- 

 minous gleam occupied certain portions of the body and fins, its 

 permanence during life, and decline and cessation upon the ap- 

 proach and occurrence of death, did not leave a doubt in my mind 

 but that it was a vital principle, essential to the economy of the 

 animal. 



The small size of the fins would appear to denote that this fish 

 is not active in swimming ; and since it is only predaceous, and 

 evidently of nocturnal habits, we may perhaps indulge the hypo- 

 thesis, that the phosphorescent power it possesses is of use to at- 

 tract its prey, upon the same principle as the Polynesian islanders 

 and others employ torches in night fishing. — Bennefs Voyage, 

 vol. ii. p. 255. 



19. The " Trochilus and Crocodile'* of Herodotus.. — Mr Wilkin- 

 son, in his excellent work on Egypt, vol. iii. p. 79, says : " Hero- 

 dotus enters into a detail of the habits of the crocodile, and relates 

 the frequent repeated story of the trochilus entering the animal's 

 mouth during its sleep on the sand banks of the Nile, and relieving 

 it of the leeches which adhere to its throat. The truth of this as- 

 sertion is seriously impugned, when we recollect that leeches do 

 not abound in the Nile ; and the polite understanding supposed to- 

 exist between the crocodile and the bird, becomes more improbable 

 when we examine the manner in which the throat of the animal is 

 formed ; for having no tongue, nature has given it the means of 

 closing it entirely, except when in the act of swallowing, and, 



