KCHINUXt:. 



KOHINID.^. 



Motion U (ubdirided into two, according to the extent of the ambu- 

 bera. the finrt (ex. & ntglebotut), with ambulacra only reaching the 

 circumference; the Moond (ex. & contain*, Anunchitc* conltttiu, 

 Lam.), with ambulacra reaching to the border. 



De BlainrUle auppon* that the Spotaivji are nourished with the 

 animal matter* which are mingled with the Band ; for their inteatinal 

 ^^.l, which is thin u a spider's web, was always found by him full 

 of fine sand. 



Anmekiia (fossil only). Body oval in its longer diameter (from 

 before backwards), rounded and a little wider, but without a furrow, 

 anteriorly, subcarinated posteriorly, conical, elevated at its summit, 

 which U mesial, entirely flat below, covered with a very few small 

 scattered tubercles. Ambulacra, to the number of five, rather large, 

 divergent, comprised between double lines of pores but little approxi- 

 mated, and scarcely overpassing the borders. Mouth and vent sub- 

 terminal and inferior. De Blainville subdivides this genus into two - 

 sections ; the first, with the ambulacra prolonged up to the borders 

 (Atuatdule*. Lam.), ex. A. mat**; the second, with the ambulacra 

 prolonged up to the mouth (Eckinocoryt, Leske, Gray ; Gaiea, Galeota, 

 Klein), ex. A. piutulotta, EMiiocuryta puitulotui, Leske. 



Sub-Family 2. Paracentrattomata Edentata. 



ffucleolita (fossil only). EMaobritnu of Breyn and Gray, adding 

 the Cauiduhe. Body oval or heart-shaped, wider and with a large 

 furrow behind, rather convex, the summit sub-central and mode- 

 rately elevated above, somewhat concave below ; covered with small 

 equal and scattered tubercles. Ambulacra, to the number of five, 

 subpetaloid, open at the extremity, dorsal and marginal, and con- 

 tinued by as many furrows up to the mouth, which is inferior, Hub- 

 central, and anterior. Vent sub-central, above, in the furrow. Genital 

 pores to the number of four. Ex. A', depranu, Spatangut depremu, 

 Leske, Klein ; Clypeut lobattu, Fleming. 



The specie* are tolerably numerous and are frequent in the Chalk, 

 but are also found in the beds anterior and posterior to it. 



EfkHiodypau (fossil only). Body depressed or conical, circular or 

 inclining to oval, with a furrow behind, convex and with a sub-central 

 summit above, rather excavated below, formed of distinct plates and 

 covered with very small equal tubercles. Ambulacra to the number 

 of five, dorso-marginal, *ub-petaloid ; the double rows of pores united 

 by a transverse furrow. Mouth sub-central, a little more anterior, 

 pentagonal, with five converging ambulacriform furrows. Vent 

 entirely above, behind the summit, and at the origin of the posterior 

 furrow. Genital pores to the number of four. 



EchinolamjHU, Gray. (Ediinanltau t Leske). Body oval or cir- 

 cular, depressed, sub-convex above, rather concave below, rounded 

 and widened forward, rather narrowed towards the anal extremity, 

 composed of great polygonal plates and covered with spines, probably 

 very small Ambulacra, to the number of five, sub-petaliibrm, not 

 closed at their extremity, and nearly approaching the border. Mouth 

 round, sub-central, and nevertheless a little anterior. Vent entirely 

 marginal, terminal. Genital pores four only in number. Kx. K. 

 orimtalu (recent). 



Catridula. Body oval, more or less depressed, composed of 

 indistinct plates and covered with small spines. Ambulacra five, 

 dorsal, rarely marginal. Mouth below, submedian, in a stelliform 

 notch. Vent postero-dorsal, or above the border. Genital pores four. 



De Blainville subdivide* this genus into the following section* : 



a. Specie* whose ambulacra form a dorsal star, and whose mouth 

 is at the bottom of a stelliform impression. Ex. C. Lapit Cancri. 



JS, Species whose ambulacra are prolonged to the border and not 

 closed. Ex. C. Atutralit. 



t. Species whose ambulacra are not known to De Blainville. Kx. 



De Blainville observe* that this genus (Lamarck'*) is evidently 

 artificial. Goldfuss unite* the genus with Nuclmtita. 



Fibnlaria. Body globular, but rather higher than it is wide, 

 ribbed, a* it were, with about 20 ribs, formed probably by so many 

 rank* of polygonal scales, and covered with very fine spines. 

 Ambulacra five, very abort, and not shut at the extremity. Mouth 

 round, cub-central. Vent inferior, and much approximated to the 

 mouth. Genital pore* unknown. Ex. F. craniularit. 



This genus was established by Van Phelsum and by Leike, under 

 the denomination of cAuiocyamtu, adopted by Dr. Gray. K. ptuiJIat 

 u a British specie*, and Professor K. Forbes says it is one of the 

 connecting link* between the true Eckiai and the Spatangacea;. It 

 has the teeth of the former and the spines of the Utter. It is the 

 lea*t of all the Britiah specie*, and one of the smallest of the family. 

 Mr. Forbes MY*, " I believe the fAularia owlum and /'. tarentina 

 at Lamarck, and the F. anyutota of Dealongchamps, will all prove 

 to be identical with this species." 



Krkinvnttu. Body rounded or oval, generally excavated below, 

 compoeed of plate* often distinct and covered with small spine*. 

 Ambulacra five, Urge, complete, radiating from the dorsal centre to 

 the mouth, and formed by ambulacra] lines, which are very close and 

 impressed. Mouth central or cub-central, without teeth, and pierced 

 in a sub-triangular hole of the shell. Vent towards the border below 

 or even above, in a longitudinal and sulmymmetrical hole of the 

 shell. Genital pore* four. 



De Blainville subdivides the genus into the following sections : 



a. Oval species, with the anal hole longitudinal and below. Kx. 

 5. minor. 



/3. Circular specie*, with the vent below and round. (D'ucoidta, 

 Gray). Ex. E. nbucvliu. 



y. Oval species, with the vent entirely marginal, and the genital 

 wres to the number of seven (!) Ex. E. oral it. 



8. circular specie*, which are depressed and have a margino-dorsal, 

 non-symmetrical anal opening. Ex. E. cattidularit. 



Sub-Family 8. Paracentroitomata Dentata. 



Mouth subcentral, in a regular notch of the shell, and provided 

 with teeth. 



locyavmt. Body depressed, oval, wider behind than before, a 

 little excavated below, covered with rounded tubercles pierced at 

 the summit anil rather large in proportion, supported internally by 

 live double inferior ribs, terminating round the buccal notch by as 

 many simple apophyses. Ambulacra dorsal, not marginal, completely 

 open at the extremity, a little enlarged, and forming a sort of cross 

 with dilated branched. Buccal opening sub-central, regular, armed 

 with five teeth as in Clypeatter. Vent below, between the mouth and 

 the border. Genital pores four. Ex. E. minutta. 



De Blainville states that he characterised this genus from a con- 

 siderable number of individuals of a very small species found in the 

 intestines of a turbot, and which occurs in great quantity in the 

 sand of the coasts of the English Channel, according to Pallas, both 

 on the French and English shores. He adds that, very probably, it 

 is the Fibularia orulum of Lamarck ; and that, without doubt, 

 Fibularia tarentina belongs to this genus, as well as Echinonna 

 placenta of Goldfuss. 



Lay ana, Gray (Ecltinodisciu, Van Thelsum, Leske). Body depressed, 

 circular or oval lengthwise, a little convex above, concave below, with 

 an entire disc and borders, composed of plates, but little distiiu-t 

 and covered with scattered spines. Ambulacra five, regular, petoloid, 

 shut, or nearly so at the extremity, with the pores of each side 

 united by a furrow. Mouth median in the middle of a hole, with 

 converging furrows oud furnished with teeth. Vent inferior, pierced 

 in a regular hole, situated between the mouth and the border. Genital 

 pores five. The genus is thus subdivided by De Blainville : 



a. Circular species. Ex. L. orbicularit. 



B. Oval species. Ex. L. oralit. 



y. Polygonal species. Ex. L. decagona, 



The genus approximates to Ctypeatttr, under which Lamarck 

 arranges the species. 



Clypeatter. Body much depressed, rounded and rather thick on 

 the borders, sometimes incompletely orbicular or radiated, enlarged 

 towards the anal extremity, composed of large and unequal plates, 

 covered with very small, equal, scattered spines supported on \rry 

 small tubercles pierced with a pore. Ambulacra constantly five in 

 number, dorsal, petaloid, the two rows of pores of each branch 

 united by a furrow. Mouth central or sub-central, at the bottom 

 of a sort of tunnel, formed by five grooves and armed with five 

 teeth. Vent terminal and marginal. Genital pores to the number 

 of five. 



The living species are but few. They inhabit the sea* of warm 

 countries in Asia and America. Ex. C. rotaceut. 



The fossil species are more numerous and are generally from the 

 Tertiary Bed*. 



Ecliinoditcut. Body rounded, depressed, sub-qmnquolobated itiir 

 posterior lobe a little notched in the median line), rather < 

 above, concave below, composed of plates in 20 rows, placed tv. 

 two. The ambulacroire* narrower and covered with very small, fine, 

 close-set spines. Ambulacra to the number of five, diverging by the 

 complete separation of each double line of pores. Mouth in 

 round, towards which converge five straight and st. Hi form furrows. 

 Vent marginal Genital pores to the number of four. Kx. / 

 /''. i. 



EckinoracKntui placenta, Gmelin, the Cake-Urchin of Forbes, in the 

 Echinoditctu placenta of Blainville. icenta of Lamarck. It 



is described by Forbes as a British species. It ha* however been 

 seldom taken on our coast*. 



ScMtdla (tfcUita, Klein ; Echinodisau, Leske). Body irregularly < ir- 

 cular, wider behind, extremely depressed, borders nearly sharp-edged, 

 sub-convex above, a little concave below, composed of large polygonal 

 scales, and covered with very small uniform and scattered spines. 

 Ambulacra 5, more or less petal ifonn, the two rows of pores of each 

 branch united by transverse furrows, which makes them ) 

 striated. Mouth median, round, furnished with teeth, and towards 

 which converge five vasculiform furrows more or less ramified, and 

 sometime* bind from the base. Vent always inferior and at some 

 distance from the border. Genital pores 4. 



The recent species of Sculella are arranged as follows : 



a. Species whose disc alone is perforated. Ex. S. hexapora. 



ft. Species whose disc and borders ore perforated. Kx. X titrapora. 



y. Specie* whose border only is notched. Ex. S. aurila. 



S. Species whose disc and border ore entire. Kx. .V. intcyra. 



. Species whose disc is perforated and their bord> -Hated. 



Kx. S. octoJaclyla. 



