111 ZOOLOGY. 



an immense rorqual may be seen raising his enormous back 

 at intervals from the water, and is to be observed coursing 

 round and round the island. 



" I have examined great numbers of these cetaceous animals 

 (dolphins and porpoises) within the last few years, and never 

 have seen anything resembling the remains of herrings, or 

 fish of any other kind, in the stomach, although the former 

 fish was very abundant at the same time in the Firth. I 

 make no doubt, therefore, that the cetacea only accompany 

 the herring in pursuit of their common food, viz., entomos- 

 traca and acalephse. 



" I have already stated that it was entomostraoous animals 

 which formed the great mass of the maidre. Among these 

 I obtained a great number of nondescript species, one of 

 which I shall now describe. 



" On one of my occasional visits to the Isle of May, I ob- 

 served that at a considerable distance from the island the sea 

 had a slightly red colour, that this became deeper and deeper 

 as we neared the island ; and also that the surface of the 

 water presented a very curious appearance, as if a quantity of 

 fine sand were constantly falling on it. I thought at first 

 that this last circumstance proceeded from rain, but presently 

 I found that both phenomena were caused by a great number 

 of small red entomostraca, which I had never before observed 

 in such abundance. On further observation, I found that it 

 belonged to the genus Cetochilus of M. Rousel de Vauzeme, 

 who has given a detailed description of his species (C. Aus- 

 tralia), the only one hitherto known, in the first vol. of the 

 Annales des Sciences Naturelles, This author states, that 

 it is found in the Pacific Ocean, and in the middle of the 

 Atlantic Ocean, about 40 degrees south latitude. It forms, 

 he says, very extensive banks, which impart a red colour to 

 the water, and which furnish a plentiful supply of food to the 

 whales frequenting those seas." R. K.] 



572. The division of podophthalmaria comprises tin- 

 greater number of Crustacea, and is composed of all those 

 whose organization is the most complex and the most perfect. 

 It is subdivided into two orders, the decapoda and the 

 stomapoda. 



573. The order of the decapoda comprises the crabs, 

 lobsters, and all the other Crustacea in whom the .branchiju 

 are internal, and in whom the limbs are five pairs in number. 

 The head and the thorax of these animals are confounded 



