ECHINODERMATA. 



787 



genus of fishes of the order thoracki. Generic 

 character : head furnished on the top with a flat, 

 oval, transversely grooved shield ; gill-membrane, 

 with ten rays, according to Gmelin, and six, accord- 

 ing to Shaw ; body not scaled. There are three 

 species. The echineis remora, or Mediterranean 

 remora, is of the length of from twelve to eighteen 

 inches. Among the ancients its peculiarity or struc- 

 ture and habits was connected with the most incredi- 

 ble and marvellous circumstances, which are, how- 

 ever, detailed with all possible gravity and faith, by 

 their most profound naturalists. Pliny states, tliat 

 the force of the tide, the current, and the tempest, 

 joining in one grand impulse with oars and sails, to 

 urge a ship onwards in one direction, is checked by 

 the operation of one small fish, called remora by the 

 Roman authors, which counteracts this apparently 

 irresistible accumulation of power, and compels the 

 vessel to remain motionless in the midst of the ocean. 

 He credits the prevailing report, that Antony's ship, 

 in the battle of Actium, was kept motionless by the 

 exertion of the remora, notwithstanding the efforts of 

 several hundred sailors ; and that the vessel of Cali- 

 gula was detained between Astura and Antium by 

 another of these fish found sticking to the helm, and 

 whose solitary efforts could not be countervailed by 

 a crew of 400 able seamen, till several of the latter, 

 on examining into the cause of the detention, per- 

 ceived the impediment, and detached the remora from 

 its hold. The emperor, he adds, was not a little 

 astonished, that the fish should hold the ship so fast 

 in the water, and, when brought upon deck, appear 

 to possess no power of detention over it whatever. 

 This confiding naturalist expresses himself as per- 

 fectly convinced that all fishes possess a similar 

 power, and states, as a notorious example, the deten- 

 tion of Periander's ship by a porcellane, near the 

 cape of Gnidos. Quitting, however, the fables of 

 antiquity, it may be observed, that the fins of the 

 remora are particularly weak, and thus prevent its 

 swimming to any considerable distance, on which 

 account it attaches itself to various bodies, inanimate 

 or living, being found not only fastened to ships, but 

 to whales, sharks, and other fishes ; and with such 

 extreme tenacity is this hold maintained, that, unless 

 the effort of separation be applied in a particular di- 

 rection, it is impossible to effect the disunion without 

 the destruction of the fish itself. As the remora is 

 extremely voracious, and far from fastidious in its 

 food, it may attach itself to vessels and large fish 

 with a view to secure subsistence. This fish will 

 often adhere to rocks, and particularly in boisterous 

 and tempestuous weather. The apparatus for accom- 

 plishing this adhesion consists of an oval area on the 

 top of the head, traversed by numerous dissepiments 

 each of which is fringed at the edge by a row of very 

 numerous perpendicular teeth, or filaments, while 

 the whole oval space is strengthened by a longitudi- 

 nal septum. It is reported by some authors, that 

 in the Mozambique channel, a species of remora is 

 employed by the natives of the coast in their pursuii 

 of turtles with great success. A ring is fixed neai 

 the tail of the remora, with a long cord attached to 

 it, and, when the boat has arrived as near as it wel 

 can to the turtle, sleeping on the surface of th< 

 water, the remora is dismissed, and immediately pro 

 cmls towards the turtle, which it fastens on so 

 firmly, that both are drawn into the boat with grea 

 ease. 



ECHINODERMATA ; the tenth class of inver 

 tebrate animals, or such as are devoid of a backbone 

 These animals have a suborbicular body, protectet 

 by a coriaceous or crustaceous covering. They an 

 radiated, and destitute of a head and eyes, and have 

 not articulated limbs ; the mouth is placed beneath 



uul is either simple or multiform ; the organs of 

 ligestion are compound ; and the covering is pro- 

 ided with exterior tubes or pores for respiration. 



The older naturalists arranged this class of ani- 

 mals among the testaceous mollusca, others placed 

 hem in the class zoophytes ; and in more modern 

 imes they occupied a situation among the crustaceous 

 animals. 



The strict attention which has recently been 

 jaid to comparative anatomy, has enabled physiolo- 

 gists to form more distinct and decided zoological 

 arrangements, founded principally on their internal 

 structure ; in consequence of which this group of 

 animals has been formed into a separate class by 

 amarck", who placed them as the first of the great 

 division of radiated animals. 



Besides the external distinctions which we have 

 above given, the internal cavity is furnished with dis- 

 tinct viscera, and a sort of vascular system maintains 

 a communication through the different parts of the 

 intestine, and with the respiratory organs. These 

 consist of pores or orifices, or tubes placed on the 

 exterior covering for the passage of water. Their 

 nervous system is but indistinctly traced, and 

 they have but extremely imperfect organs of mo- 

 tion. 



The whole of the animals constituting this class, 

 inhabit the ocean, and, like many other of the lower 

 animals, have the power of regenerating parts of 

 then- bodies which have either been injured or broken 

 off. 



Lamarck divides the Echinodermata into three 

 sections, under the names Fistulides, Echinides, and 

 Stellerides ; and we have followed Mr Millar in add- 

 ing a fourth section, which he names Crinoidae, 

 formed from the Encrinites. 



SECTION I. FISTULIDES. 



Body elongated, cylindrical, soft and very retractile ; covered 

 by a soft mobile and irritable skin. 



Tliese animals respire through tho medium of water by 

 pores or tubes, which are retractile, and inhabit the sea 

 shores. 



The genera are Sipunculus, Priapulus, Holothuria, and 

 Fistulaiia digitata, pl.32. f 3. Body free, soft and cylindri- 

 cal ; covered with a very rough and tubercular coriaceous 

 skin ; mostly terminal, surrounded with dilated tentacula at 

 the summit, the flattened part divided or dentated ; anal vent 

 at the posterior extremity. 



SECTION II. ECHINIDES. 



With a solid immovable crust or shell ; body snbglobular or 

 depressed, destitute of radiating contractile lobes; mouth and 

 anal opening distinct ; tubercles on th exterior surface ; tlie 

 shell immovable, but the spines susceptible of motion. 



The differences of the animals of this section require to be 

 formed into two sub-sections. First, those haying the anal 

 opening above the margin and dorsal, and vertical, and with 

 a regular shell. The genera :ire Cidarites, and 



Echinus esculentut, pi. 33. f. 1. With a regular, gibbous, orbi- 

 cular, globular, or oval body ; shell solid, crustaceous, and pro- 

 vided externally with irapertorate tubercles, upon which are 

 articulated movable spines; compartments five, each margined 

 by two multiporous divergent bands, extending in rays from 

 tlie summit to the mouth, which is inferior, central, and armed 

 with five bony enamelled pieces ; anal opening above. 



This sub-section is again subdivided into animals with a dor- 

 sal anal opening, but approaching tlie margin. The genera are 

 Nucleolites and Cassidulus. 



The second sub. section consists of animals whose anal open- 

 ing is under the margin of the disk, or on the margin. This 

 is again subdivided into, first, those with the mouth beneath, 

 not central, but approaching tSu- margin. The genera are .An. 

 anchytes, and 



Spatangui purpureiu, pl.32 f. 5. Having an oval or cordifnrtn 

 andsubgibbous body, covered with yery small spines ; from four 

 to live unequal compartments ; mouth laMated transverse, 

 approaching the margin ; anal opening lateral, placed opposite 

 the mouth. 



The animals of this section are known by the familiar names 

 of sea urrhines, sea eggs, &c. 



SECTIO.N III. STELLERIDES. 



Having a coriaceous, but not irritable skin, which is mov- 

 able in certain points ; body short, depressed, broader than 

 long, provided with marginal lubes, more or less numerous, 

 radiating and movable ; no anal opening. 

 The genera are Ophiura, Euryale, Comatula, and 

 Aitenat rubent, pl.32.f.2. With a suborbicular depressed body, 

 divided in its circumference into angles, rays, nr lobes, disposed) 

 in a stellated form ; under surface of the rays provided with & 

 3 n 2 ' 



