465 



ECHINID^E. 



ECHINOCYAMUS. 



4C6 



f. Species whose disc is imperforate and the border multiradiated- 

 (Demi-Soleils.) Ex. S. denlata. 



The living species whose habitat is known are foreign, and the 

 South Seas appear to be their principal locality. 



The fossil species are tolerably numerous, and occur generally in 

 the Calcaire Grossier of Paris, Grignon, and the environs of Nice. 



Sub-Family 4. Ctntrottomata. 



Mouth quite central. Summit median. Body regularly oval or 

 circular, covered with tubercles and m:unilla\ and consequently with 

 spines of two sorts. Vent variable, ordinarily medio-dorsaL 



Galeritet (fossil only) ; Conulut, Klein ; Echinoconu, De Blaiuville. 

 Body nearly regularly circular or polygonal, entirely flat below, con- 

 vex and often conical, with the summit median above, formed of very 

 dissimilar plates, and covered with tubercles of two kinds. Ambulacra 

 complete, narrow, to the number of 4 or 5, dorso-buccal. Mouth cen- 

 tral, and probably armed. Vent infero-marginal. Genital pores to the 

 number of 5. The species may be placed in two sections. 



a. Species with 4 ambulacra, and consequently with C series of 

 plates. Ex. G. quadrifaaciatiu. 



P. Species with 5 ambulacra. Ex. G. rulgarit. 



y. Species with 6 ambulacra. Ex. G. stjfaeciatiu. 



The genus is often found silicified and in casts. The greater portion 

 belong to the Chalk, and a small number to the beds anterior to the 

 Chalk. None have as yet been found in the more recent strata. 



Krhinometra (Gray). Body thick, solid, transversely oval, a little 

 depressed, convex, with the summit (which is median) flat above and 

 arched below, covered with inamillated tubercles of two sorts, and 

 bearing diversiform but always strong and large spines. Ambulacra 

 5, enlarging themselves below. Buccal opening of the shell large, 

 transverse, with very powerful auricles on its internal circumference. 

 Five sharp teeth at the mouth, with a complicated apparatus, as in 

 Eckinia. Vent medio-superal, or opposed to the mouth. Genital pores 

 to the number of 5. Ex. E. atrata. 



The species are found in the seas of warm climates. They are 

 unknown in those of England and France. 



A'cAi'iiiM. Body in general very regularly circular or sub-polygonal, 

 sometimes slightly transverse, composed of 20 radiated rows, alter- 

 nately unequal, of polygonal plates bristled with diversiform spines 

 of two kinds, and supported on imperforate mamillated tubercles. 

 Ambulacra constantly to the number of 5, and complete. Mouth cen- 

 tral, armed with 5 pointed teeth, supported upon a very complicated 

 internal apparatus. Vent median, superior, or exactly opposite to the 

 mouth. Genital pores to the number of 5. 



The food of the species of Echinm is generally believed to consist 

 of mollusks and crustaceans. Tiedemann found in . lajcatilii small 

 univalve and bivalve shells entire smong the excrements, as well ns 

 fragments of larger ones. Bosc is said to have witnessed an Echinut 

 in the act of seizing and devouring a small crustacean. Dr. Sharpey 

 usually found in the intestine of E. esculent m small morsels of sea- 

 weed for the most part encrusted with Pluttra ; and he says that the 

 excrements, which are in the form of small round pellets about the 

 size of peppercorns, consist chiefly of sandy matter with fragments of 

 shells. But he adds that it would be difficult to say whether these are 

 the remains of digested Mollusca or merely a portion of the usual 

 testaceous debris so abundant in sand and mud. 



The species of this genus are most abundant in all the seas of 

 Europe. Several very fine species are natives of the Mediterranean. 

 The following are British species : 



B. tphara, the Common Egg-Urchin, Sea- Egg, ' Sea' ad Manshead.' It 

 is the E. marinut of Lister ; . eiculentia, Pennant ; . ylMfarmit, 

 Lamarck. It has the following characters : Rows of pores obliquely 

 [parallel, three pairs of pores in each row ; spines thick, conic, longi- 

 tudinally striate ; striic broader than the ridges, and transversely 

 striated ; primaries scarcely longer than secondaries. (Forbes.) The 

 Common Sea-Urchin is usually of a reddish or purplish colour with 

 white spines. These are in some specimens tipped with purple. It 

 lives in various depths of water, extending its range from the littoral 

 mine to that of the corallines. It is found in greatest numbers on a 

 clean sea-bottom, but inhabits all the shores of Great Britain and 

 Ireland. It is eaten abroad in the same manner as Echinva ecvlmtu. 

 Pennant says it is also eaten amongst the poor in England. The 

 ancient* deemed it a dainty dish, and ate it both raw and cooked in 

 various ways. They are best when full of eggs, which is in the autumn. 



E. miliaru (Leske), the Purple-Tipped Egg-Urchin, has the following 

 characters: It is depressed, the rows of pores not parallel, three 

 pairs of pores in each row ; spines longitudinally striated, shining, 

 smooth ; striae narrower than ridges ; primaries long. (Forbes.) This 

 is a small species, and is found in company with the lost, from which 

 it may at once be distinguished by its long purple spines. It is 

 abundant in the Irish Sea, as also on the west coast of Scotland. 



. Plcmingii, Fleming's Egg-Urchin. It is the E, miliarit of Flem- 

 ing, but is undoubtedly a distinct species. It is the largest of the 

 British species, measuring from 10 to 14 inches in circumference. It 

 has the following characters : Rows of pores sub-parallel, three pairs 

 in each row ; primary spines thick, much fewer than the secondary, 

 and nearly thrice as long ; spines longitudinally striate ; stria: some- 

 what narrower than the very narrow ridges. (Forbes.) 



H AT. HIST. DIV. VOL. II. 



. limdtts (Lamarck), Purple Egg-Urchin. It is the E. saxatilis of 

 Linnaeus ; E. lithophagus of Leach. It has the rows of pores bent, 

 five pair in each row above and centrally, but diminishing in number 

 near the mouth ; spines striated ; ridges broad, smooth ; primary 

 spines longer than secondaries. (Forbes.) In the British Isles this 

 species is peculiar to Ireland, where it is chiefly found in the south. 

 It is always stationary, never quitting the cup-like hole which it 

 appears to form with its spines. 



E neglectw (Lamarck), Silky-Spined Egg-Urchin ; . sulangularis, 

 Fleming. Rows of pores beet, five pairs in each row throughout; 

 spines thick, conic, glistening, longitudinally striate ; strise and ridges 

 equal, transversely striated ; primary spines scarcely longer than 

 secondaries. This species has been taken on the coasts of Scotland. 



All the species of Echinus present upon their integument a number 

 of bodies called Pedicellarice. Whethel- they are parts of the animal 

 or parasitic animals has not been decided by naturalists. They are 

 however curiously characteristic of many forms of Echinus as of other 

 species of Echinodermata. [PEDICELLARIA.] 



For further remarks on the Echinidce, and their fossil forms, in con- 

 nection with the other species of Star-Fishes, see ECHINODEHMATA 



ECHINOBRISSUS. [ECHINID.E.] 



ECHINOCACTUS, a genus of Plants belonging to the natural 

 order Cactaceee. The stem is of an ovate or spheroidal form, the 

 sides being divided into many ribs, upon whose projecting angles are 

 stationed at short intervals little spiny stars, which are the rudiments 

 of leaves, and from whose centre the flowers appear. The latter 

 consist of numerous sepals collected into a tube, an equally large 

 number of petals, numerous stamens, and a filiform style divided into 

 many lobes at the point. The species are very remarkable for the 

 singular forms of their stems, and for the curious manner in which 

 their spines are arranged. They are often moreover conspicuous for 

 the beauty of their large flowers. The genus is extremely near Cereus, 

 from which, according to De Candolle, it only diners in having the 

 sepals and petals distinct from each other, not united into a tube. 

 But as C. triangularit has its sepals distinct, and all the Echinocacti 

 have more or less of a tube, we consider it better to limit the latter to 

 such species as have a depressed or spheroidal form. With such a 

 limitation the Cereut Eyresii, one of the moat beautiful of plants, 

 will really belong to the genua Echinocacttu, of which it has all the 

 habit ; otherwise it would be a Cereut, to which its stems bear but 

 little resemblance. There are above 30 species enumerated. Most 

 of them are natives of Mexico and the West Indies. A few are 

 found in Brazil. They are known by the name of Hedgehog Thistles. 



Echinocaclus Eyrcsii. 



ECHINO'CHLOA (from ixivos, a hedgehog, and x\6i>, grnas), a 

 genus of Grasses belonging to the tribe Paniceie. It has compound 

 spikes secund in the whole and in each part ; spikelets on one side of 

 a flattened rachis, 2-flowered, the inferior flower rudimentary ; 2 

 glumes, the lower small, 3-nerved, the upper as long as the flower, 

 5-nerved mucronate ; the outer palea of the sterile flower resembling 

 and equalling the upper glume. This is a genus of coarse grasses, of 

 which only one species, the . Crui-Galli, grows in Great Britain. It 

 is a strong coarse grass, bearing any climate better than most others, 

 and is found in the vicinity of London. (Babington, Manual.) 



ECHINOCIDARIS. [ECHINUS.] 



ECHINOCLYPEUS. [ECHINID*.] 



ECHINOCOCCUS. [ENTOZOA.] 



ECHINOCONUS. [EcHiniDJS.1 



ECHINOCORYS. [EcmuiD*.] 



ECHINOCYAMUS. [EOHUnn*.] 



2 B 



