CLASS OF CRUSTACEA. 487 



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., entomostraca and acalepha.' 



"I. have already stated that it was entomostracous 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 observed 

 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 pre- 

 sented 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 abun- 

 dance. 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. Australis), 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 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 the 

 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 branchiae 

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

 The head and the thorax of these animals are confounded 

 into a mass covered by a large carapace or case (Fig. 517) ; 

 this dorsal buckler advances in general more or less in front, 

 descends on each side to the base of the limbs, and backwards 

 as far as the origin of the abdomen (Figs. 504, 507). It results 

 from this arrangement that we can no longer recognise 

 throughout all this part of the body any trace of an annular 

 division ; but beneath, most of the rings, although united 

 together, are still recognisable, and leave at their points of 

 junction the lines of suture, more or less distinct. The eyes 



