642 



ECHINODERMATA. 



of them as a principal ingredient in restorative soups. The Malays catch and dry them in great quan- 

 tities for the Chinese markets, where they fetch a high price, and are called tre-pang.] 



THE SECOND ORDER OF THE ECHINODERMATA. 



APODA. 



The number of known species in this order is but few. 

 the feet ; and their leather-like skin is quite unarmed. 



They resemble Holothuria:, but want 



Molpadia, — 

 Have the form of the body and the internal structure similar to those of Holothuria, but they have no 

 feet or tentacula, and the bony parts of the mouth are less complicated than in the Echini. 

 M. holothurioides, of the Atlantic ocean, was the only species known to Cuvier. 



MlNYAS, 



Have the body without feet, but of a spheroidal form, and furrowed like a melon. 



M. cyanea, is a beautiful species, of a dark blue colour, inhabiting the wanner parts of the Atlantic ; the mouth 

 in this genus has neither tentacula nor bony plates. 



Priapulus, — 

 Have the body cylindrical, with deep annular rugae, and terminated anteriorly by an elliptical and longi- 

 tudinally wrinkled mass, in the centre of which is the mouth, with numerous teeth arranged in quin- 

 cunx, and having the points turned backwards. The muscular system resembles that of Holothuria. 

 P. vulgaris, the only known species, inhabits the northern seas, and is from two to three inches in length. 



LlTHODERMIS, 



Have the body oval, compressed in the hinder part, and covered above with an extremely hard granu- 

 lated crust ; the mouth has tentacula, but Cuvier discovered no second opening to the body. 



Only one species, L. cuneus, from the Indian seas, about two inches long, and of a blackish colour, was known 

 to Cuvier. 



Siphunculus, — 

 Have the body long and cylindrical, and wrinkled both longitudinally and across ; the mouth is an 



extensile and retractile proboscis ; the intestine straight for nearly 

 the whole length of the body, and then returning in a spiral upon 

 itself. In these, and indeed in most of the order, there are threads 

 iwhich appear to be nerves, and in this genus the breathing apparatus 



Fig. 139.-Siphanculus. are Qn tne s j(] eS) anc } p en near the Vent. 



There are a good many species, most of which live in the sand, though some small ones perforate submarine 

 rocks, and lodge in the cavities. S. edulis, which is eaten by the Chinese in the Oriental islands, occurs also in 

 the salt lakes of Languedoc. They are used by the fishermen as bait. Some Indian species are nearly two feet 

 long. They used to be classed with worms, but their organization is quite different. 



BONELLIA, 



Have the body oval ; the proboscis very extensile, and forked at the extremity : their intestinal canal 

 is long and convoluted. What appear to be the organs of respiration are situated near the vent ; and 

 the ovary is an oblong sac which opens near the base of the proboscis. They inhabit the sand at a 

 considerable depth, and can elevate their proboscis to the water, or even to the air, where the water is 

 very shallow. 

 B. viridis, of a green colour, and is found in the Mediterranean. 



Thalassema, — 

 Have the body oval or oblong, and the proboscis in the form of laminae, resembling the bowl of a spoon, 

 but not forked. The intestinal canal resembles that of the preceding genus, but they have only one 

 abdominal thread. 

 They are distinguished into Thalassema proper, which have two lateral hooks placed considerably in advance, 



