On Cyrtoma, a neiv genus of Fossil Echinida. 177 



to discover the true position of our new genus, it is un- 

 necessary to enter further into the question at present. 

 It is one of those subjects that seems to have been al- 

 most altogether neglected, and it is a curious fact, that 

 if we except the discovery of fossil forms which we owe 

 chiefly to geologists, and the researches of comparative 

 anatomists, the natural history of these animals remains in 

 almost as much obscurity as in the time of Aristotle, who 

 was acquainted with both sea-stars and sea-urchins, and who 

 separated the latter from Spatangi. In his system he 

 arranges them with Testacea, but he alludes to them in 

 another place as equivocal beings, between the animal and 

 plant; and to this day a similar uncertainty has prevailed 

 on the subject, Cuvier placing them at the head of his zo- 

 ophytes, and Mr. MacLeay, the first who has cast a clear 

 light on the natural relations of animals, conceiving that 

 they ought to follow the Crustacea, thus raising them to a 

 higher rank than that in which they were regarded by 

 either Aristotle or Cuvier. With regard to the Holo- 

 thuria, they are still less known from their being less 

 beautiful, and consequently less likely to attract the notice 

 of collectors. Fortunately for science, it has been found 

 within the last few years that although neglected and 

 despised by enlightened Europe, various species of Holo- 

 thuria have yielded a trade of considerable extent between 

 most of the maritime nations of Asia and the Chinese, a cir- 

 cumstance which may now lead to their investigation. 



In Crawford's Indian Archipelago, we learn that the Tre- 

 pang, or sea-slug, called by Europeans Beche de mer, is found 

 chiefly on coral reefs in the Eastern seas, and is highly 

 esteemed in China, into which it is imported in large quan- 

 tities. It is said to be an unseemly substance, of a dirty 

 brown colour, hard, and rigid, scarcely possessing any power 

 of locomotion or appearance of animation. It varies from a 

 span to two feet in length, and from two to eight inches in 

 circumference. The value and use of the animal do not 



