42 ZOOLOGY. 
senting the ambulacra, or confined to the middle portion of the ventral. 
surface. The mouth is fringed with branching tentacles capable of being 
withdrawn ; the vent is at the opposite extremity of the body; and the entire 
animal bears a striking resemblance to a cucumber, whence it is called by 
sailors the sea-cowcumber, and one of the genera bears the name of 
Cucumaria (C. frondosa, pl. 76, fig. 85). They are extensively collected 
bout the islands and reefs of the Eastern oceans as a culinary delicacy for 
the Chinese markets. . herr 
Captain Flinders mentions a Malay fleet. of sixty vessels and one thousand 
men, as forming an expedition to fish for these animals. 
“The object was a certain marine animal called trepang; of this they — 
gave me two dried specimens, and it proved to be the beche-de-mer or sea- 
cucumber, which we had first seen on the reefs of the east coast, and had 
afterwards hauled on shore so plentifully with the seine, especially in Caledon 
Bay. They got the trepang by diving, in from three to eight fathoms 
water; and where it is abundant, a man will bring up eight or ten at a time. 
The animal is split down one side, boiled, and pressed with a weight of 
stones; then stretched open with slips of bamboo, dried in the sun, and 
afterwards in smoke, when it is fit to be put away in bags, but requires 
frequent exposure to the sun. A thousand trepangs make a yzcol, of about 
125 Dutch pounds; and one hundred picols is a cargo for a prow.” 
Orpver 5. SreuncutipEa. These are sometimes included in the order 
Holothuridea, with which they agree in the tentacles, the intestinal canal, and 
circulatory system, although they want the tubular feet. Szpuneulus (pl. 74, 
tig. 7, and pl. (7, figs. 27, 28). According to Quatrefages the anatomy of 
Echiwrus indicates an affinity both to the cheetopodous annelida and to 
Holothuria, giving: it characteristics of distinct types. Some authors, as 
Blainville and Gervais, place these animals among the Annelida. 
Criass HELMINTHES. 
The classification of the various forms of worms has been attended with 
difficulties, some of which still remain, notwithstanding the efforts of 
distinguished naturalists to ascertain their characteristics. The worms, 
whose body is composed of a series of rings, as in the leech and earth-worm, 
and whose nervous system is composed of a line of ganglia, united by a 
double nervous cord, as in insects, form with these the division Articulata, 
of which they constitute the class Annelida. 
After excluding the Annelida from the class of worms, there still remain 
many forms, both aquatic, and living in the interior of other animals, to 
which the term Helminthes is restricted. Here the annulate structure has 
disappeared, and the median nervous system has been separated into two 
distinct branches, usually arising from a large ganglion anteriorly, or two 
ganglia united by a transverse branch. From the characteristics which 
these animals afford, it is’ difficult to decide whether they belong to the 
radiate or articulate division of the animal scale, or, as is probable, form an 
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