642 
ECHINODERMATA. 
of them as a principal ingredient in restorative soups. The Malays cateli 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. They resemble Holotburise, but want 
the feet ; and their leather-like skin is quite unarmed. 
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. 
Minyas, — 
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 warmer parts of the Atlantic ; the mouth 
in this genus has neither tentacula nor bony plates. 
Priapulus, — , 
Have the body eylindrical, with deep annular rugte, 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- 
eunx, 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. 
Lithodermis, — 
Have the body oval, compressed in the hinder part, and covered above with an extremely hard granu- 
lated erust ; the mouth has tentaeula, but Cuvier diseovered no seeond 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 retraetile proboseis ; the intestine straight for nearly 
the whole length of the body, and then returning in a spiral upon j 
itself. In these, and indeed in most of the order, there are threads 
^whieh appear to be nerves, and in this genus the breathing apparatus \ 
Fig. 139.— siphuncuius. sides, and open 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 , I 
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, I 
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. j 
They are distinguished into Thalassema proper, which have two lateral hooks placed considerably in advance. 
