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336 ECHINODERMATA. 
The Echini chiefly feed on small shell-fish, which they seize with 
their feet. Their motions are very slow. Shells of Echini are very 
abundant in the ancient strata, principally those of chalk, where they 
are usually filled with silex. 
The Echini should be divided into regular and irregular. 
In the first, 
Ecuinus, Lam.—Crpanrtis, Klein. 
Or Echinus properly so called, the shell is generally spheroidal, 
the mouth in the middle of the inferior surface, and the anus dia- 
metrically opposite. The little foramina are arranged in ten bands, 
approximated by pairs, that extend regularly from the mouth to the 
anus, like the meridian lines of a globe. 
Certain species are furnished with large and stout spines of vari- 
ous forms, placed on large tubercles on their shell, the bases of 
which are surrounded by other but smaller spines(1). 
It is among these species, as ascertained by M. Deluc, that we 
must place those whose olive-like spines are often found petrified in 
chalk, and other ancient formations, called pierres judaiques(2). 
The most common species, and particularly those of the coast of 
France, are merely furnished with slender spines, articulated on 
small tubercles that are much the most numerous. Such is the 
‘E. esculentus, L.; Klein., Lesk., I, A, B; Encyc. 132. The 
common Echinus is of the form and size of an apple, completely 
covered with short, radiating and usually violet spines. Its 
ovaries, which are reddish, and of an agreeable flavour, are 
edible in the spring. 
The neighbouring species are distinguished with difficulty, by the 
greater or less approximation of the bands of holes, the equality or 
inequality of the tubercles, &c.(3) 
(1) Echinus mammillatus, L.; Seb., MI, xiii, 1—4; Encyc., pl. 138, 139, and the 
naked shell, Ib., 138, 3, 4; The different species approximated under the name of 
Ech. cidaris, Scill., Corp. Mar. Tab., xxii; Seb., III, xiii, 8, &c.;—Zch. verticillatus, 
Lam.; Encyc., 136, 2, $;—Ech. tribulovdes, Id., Encyc., lb., 4, 5;—Ech. pistillaris, 
Id., Encyc., 137;—£ch. stellatus, L.; Seb., Ik xiii, 7;—Ech. aranezformis, 1d., tb., 
6;—Ech. saxatilis, Id., lb., 10;—ch. calamarius, Pall.; Spicil. Zool., X, ii, 1—7. 
(2) See the Letters from Switzerland of Andrez, pl. XV, and the Memoir of 
M. Deluc, Mém. des Sav. Etrang., IV, 467. F 
N.B. The naked shells are distinguished with difficulty: such are the Ech. exca- 
vatus, L.; Scill., Corp. Mar., xxii, 2, Dj—Zch. ovarius, Bourguet., Petrif., LI, 
344, 347, 348. 
(S) Ech. miliaris, Kl., 1, A, B; Encyc., 133, 1, 4—Ech. hemisphericus, Kl., U, 
