396 



ACALEPH^.- 



-RADIATA ■ 



-ACALEPHS. 



but instead of being inclosed in a shelly case, their skin 

 is only hardened with irregular scale-like or oblong 

 calcareous plates. The body is more or less elongated 

 and cylindrical, sometimes vermiform, soft or flexible 

 ill all its parts, very extensile and contractile, and fur- 

 nished with numerous suckers, by means of which their 

 movements are effected. They have a large orifice at 

 each extremity, at the anterior end of which is situated 

 the mouth, placed at the bottom of a kind of funnel, 

 wliich is surrounded, or supported throughout its whole 

 circumference, by a circle of small calcareous fibres, 

 and crowned with a circle of from five to ten branchial 

 appendages more or less plumose. These the animal 

 can at pleasure retract entirely. The reproductive 

 organs are situated near the mouth, and each animal 

 is bisexual. At the extremity opposite to the mouth 

 tlicre is situated the respiratory organ or gill, wdiich is 

 in tlie shape of a hollow tree very much branched, and 

 the animal can receive or expel water by means of this 

 apparatus, which possibly thus assists it in its locomo- 

 tion, as well as supplies air from the inhaled water. 

 Tlicse animals are, like the leeches amongst the Anne- 

 lides, exceedingly sensitive, and when disturbed will 

 sometimes contract so violently that the integuments 

 ore ruptured and the intestines protrude. The IIolo- 

 thuriuids are generally distributed through the seas of 

 (lie globe, but are congregated in the greatest numbers 

 in the Eastern seas. " On our shores," says Professor 

 Forbes, "they are rare and unattractive animals, but 

 abroad they are very abundant." Those of the Euro- 

 pean seas are never highlj- coloured, but in more tropical 

 ones, where coral reefs rise within a moderate distance 

 of the surface, as in the Red Sea and the seas to the 

 north and east of Australia, they are many of them 

 splendidly coloured. The general form of the Holo- 

 thuria; is that of a cucumber, and many of the species 

 are of a gelatinous nature and esculent. 



The species belonging to this order are numerous, 

 and are arranged in several groups or families. 



Tlie True Holothurians (Sea-cucumbers or Sea-slugs) 

 have a rather soft, somewhat elongated, subeylindrical 

 body, covered throughout with tentaculiform suckers, 

 wliich in the genus Ilolothuria form regular lines from 

 tlie mouth to the vent. 



THE NIGGER OR COTTON SPINNER {Ilohtlmria 

 vii/ra) is the onlj' species of the genus Ilolothuria that 

 is found in Great Britain. It is taken in the Cornish 

 seas in deep water, and is held in great detestation by 

 the fishermen on that coast. 



Genus Trepang. — The genus Tropang, containing 

 several edible species, belongs to this family. There 



are a great many species and varieties now known, 

 fliough formerly they were all described under one, viz., 

 Ilolothuria edulis. These animals are all natives of 

 the Indian and Australian seas, and are well known 

 under the general name of Trepang, Tripang, Biche-de- 

 mer, or Beche-de-mar. They are generally found adher- 

 ing to rocks near the shore. Some of them attain a 

 considerable size, reaching to nearly the length of two 

 feet, and the circumference of seven or eight inches. 

 These animals are much esteemed by the Chinese as a 

 nutritious article of food, and are particularly used for 

 ilavouriug their soup. They form an important article 

 of commerce amongst the natives of the islands of the 

 Indian archipelago, Cochin China, the islands belong- 

 ing to Australia, &c. Thousands of Malay proas are 

 annually engaged in this fishery, and the produce taken 

 to Canton is sold at an average for about forty-five 

 Spanish dollars per picul (= 133J lbs). Macassar is 

 the head quarters for this fishery, and about 8,333 owt. 

 are annually exported from thence to Canton. There 

 are two principal kinds of Trepang sold in Canton. 

 " The black, called coatoo, is sold to the Chinese for 

 forty dollars the ]iicul ; the white or grey, called koro, 

 is worth no more than twenty." Though the natives 

 of the Celestial Empire are verj' partial to the Trepang 

 as an article of food, Europeans do not share in their 

 taste. 



Order V.— SIPUNCULOIDEA [Siphon-worms). 



The order Sijnincidoidea is characterized by the 

 animals having a coriaceous covering, free from any 

 calcareous bodies. The mouth, or commencement of 

 the oesophagus, is not surrounded by calcareous fibres, 

 and the form of the body is cylindrical. 



The family SipuncuUdm is represented by the genus 

 Sipuncidus, which has the anterior part of the body or 

 neck retractile and exsertile. At the extremity of this 

 retractile neck is placed the mouth, which is of an 

 orbicular form, and from wliich is protruded a retractile 

 proboscis surrounded with linear tentacles. The vent 

 is situated at the side near the anterior third of the 

 length of the most swollen part of the body. 



The Six'Unculi live in the sand of the sea-shore near 

 high water mark, or amongst the debris of broken sliells. 

 Their food appears to consist of the mud of the shore, 

 mixed up with organic particles. A considerable num- 

 ber of species have been described, and not fewer than 

 ten have been found on tie British coasts. Some of 

 the species perforate submarine rocks and lodge in the 

 cavities so made, or take possession of old shells, like 

 the hermit crabs. 



Class II.— The SEA NETTLES or ACALEPHS (Acaleph^). 



The Sea-nettles, or Acalephs, form a class of interest- 

 ing creatures of beautiful structure and appearance, 

 which, however, to be fully understood, must be studied 

 on the spot where they are found. As Cuvier defines 

 them, they are animals which are found swimming in 

 tlie sea, and in whose organization may be perceived 

 vessels, which in truth are most frequently nothing but 



productions of the hitestines, hollowed in the substance 

 of the body. This body is composed of a transparent 

 gelatinous substance formed of polyhedral cells, and 

 there is only in a few to be seen any calcareous or 

 cartilaginous nucleus that can be compared to a rudi- 

 mentary skeleton. The quantity, indeed, of solid mat- 

 ter in them is so small, that Lf we take a Medusa (for 



