PEDICELLATA. 641 



penetrate into the cavity. Rotvla has one of the margins toothed like a wheel ; and some have large pores, and 

 m :.'.!• not. 



Catridului, are oval, with the vent above the margin on one side, and the lines of pores incomplete. Tli.-y are 

 distinguished by the Dumber and extent of the lines of pores, which in some species form only a rOMtteon 

 the back. 



Clypeaster, have the vent near the margin, the body depressed, the base concave, and the outline sometimes 

 angular and sometimes round. 



Fibularia, small in size, mostly globular, with the openings on the under ride, and a rosette of pores above. 



Spatangtu, have the openings below, and the rosette on the back. Some have the outline round or oval, and 

 sometimes with a deep groove on one side, making the section heart-shaped. 



Of the last, two specimens are found in the Kuropean seas; and the last, especially, has branched tentacula 

 surrounding the mouth, in which character it bears some resemblance to llolothuria. The other irregular ones 

 are chiefly fossil, and abound in various marine strata, especially in the chalk formation. 



THE THIRD FAMILY OF THE PEDICELLATA. 

 The IIolothuria (Sea-slug). 



Tnese have the body oblong, with a leather-like covering, and an aperture at each end. The mouth 

 is without teeth, or has only bony plates instead ; but it is surrounded by curiously-branched tenta- 

 cula, which the animal can, at pleasure, retract entirely; and it is also furnished with sacs for the 

 secretion of saliva. The reproductive organs are also situated near the mouth, composed of a number 

 .of ramified culs-de-sac, all opening into one oviduct. The impregnating parts are understood to be 

 some very clastic chords near the other extremity of the animal ; thus each individual is bisexnaL 

 The intestine is long, convoluted, and fixed to the covering of the body by a kind of mesentery. 

 Along the intestine there is also a double system of complicated vessels, which appear to be the organs 

 of circulation. The opposite extremity is not less curious ; for, besides the vent, it contains the respi- 

 ratory organ, or gill, which is in the 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 locomotion, as 

 v.t 11 as supplies air from the inhaled water. In the breeding season the ovaries become very much 

 extended, and contain a reddish matter, which is understood to be the spawn, or eggs. These animals 

 are exceedingly sensitive, as is the case with the Leeches among Annelidas and when disturbed, they 

 (time's contract so violently that the im ts are ruptured, and the intestines protrude. The 



subdivisions are made according to the arrangement of the feet. 



Thus, in some, as in //. phantapui, which inhabits the Kuropean seas, and has the body almost scaly, all tie 

 are on a suit disc in the middle of the body; and when they crawl, the extremities are turned up. When extended, 

 the tentacula of these are very large. 



Some, a- //. iquamata, a small species of the European seas, — but there are much larger ones in hot climates,— 

 have all the under surface soft, with numerous feet ; and the upper surface convex, sometimes supported by bony 

 plates, and the opening of the month in the form of a star. 



In others, again, the bod] >> cartilaginous, flattened horizontally, ami sharp at the edges, with the mouth and 

 feet on the inferior surface. Of these, //. regalit, found in the Mediterranean, is more than a foot long, three or 

 i u inches broad, ami crenulated at tie- edges. 



Others still, have the body cylindrical, and capable of being inflated with water. All the under side is furnished 



with feet, and the remaining parts roughened in var ■ ways. H.tmwla, common in the European seas, the 



Mediterranean especially, is an instance of tins peculiarity of form. It is of a black colour; more than ■< 

 long when inflated with water ; has the' back bristled with rofl conical point--, ami the mouth furnished with twenty 

 branched tentai ola. 



Yet, in others, the feel are arranged in five rows, like tin- ridges on a melon, of which the European s; 

 //. penacta, is more than a tout Inn-, and of a brow u colour. 



There are also mmhc, as //. papillota, which nave the bodj equally furnished with feel round it> whole - 



[The HolotfntrtCB <>( the Buropean seas, even of the Mediterranean, are not vei v numerous, neither 

 arc they brilliant in colours ; but in more tropica] seas, where coral reefs rise within a moderate distance 

 Of the surface, as in the Red Sea, ami tin' seu to the north and Ejajt of Australia, tie J art I 



numerous, and many of them splendidly coloured; so that, together with other Radiate of this ami of 



other orders, they make the sea-bottom, wlnii seen bj the light of an almOSl Vertical sun, as gaj as a 



tropical garden. The rlolothuris resemble cucumbers ; and various Ictinise, when their tentacula are 

 expanded, have as gaj an appearance ai tin flowers of almost any plants. Many of th • - are 

 esculent, and of a very gelatinous nature. Winn properl] prepared, the Chinese arc e>' fond 



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