SPH ®RECHINUS. 159 
Spheerechinus brevispinosus, Desor, Syn. Ech. foss. (1858) p. 154. 
Kchinus esculentus, de Bl. Dict. Sct. Nat. xxxvii. (1825) p. 86. 
Spherechinus esculentus, Bronn, Kl. u. Ordn. ii. (1860) pl. xxxvii. 
figs. 1-3 & 5-14, pl. xxxix. figs. 6 & 8. 
Echinus equituberculatus, de Bl. Dict. Sci. Nat. xxxvii. (1825) p. 86 
(not p. 76). 
Kchinus eequituberculatus, Desmoulins, Syn. Echin. (1837) p. 280. 
Kchinus subglobiformis, de Bi. Dict. Sci. Nat. xxxvii. (1825) p. 89; 
Desmoulins, Syn. Ech. (1837) p. 282. 
Echinus dubius, de Bl. op. cit. p. 87 ; Desm. op. cit. p. 280. 
Kchinus (Toxopneustes) albidus, 4g. § Des. Ann. Sct. Nat. vi. (1846) 
p- 367. 
Test may attain some size. Primary spines short, very numerous, 
rather blunt, white, purple, purple tipped with white, pink, red or 
brown ; secondary spines inconspicuous; pedicellarize globiferz 
enormous. 
Test hemispherical or slightly conical, not often depressed ; stout, 
thickly covered with primary tubercles. Small peristome, compact 
calycinal area, rather large periproct. 
In a typical specimen there are rather more than thirty plates in 
each interambulacral series, and those at the ambitus are about 
three times as wide as deep; they there bear six primary tubercles 
each, and this number only slowly decreases as either pole of the 
test is reached; the primary tubercles are not very prominent, but 
their large number gives a special facies to the test; scattered 
around and between them are small miliaries. ‘The primaries of the 
ambulacral plates are somewhat smaller than those of the inter- 
ambulacral; there are, at the ambitus, two on either plate, and the 
inner of these disappears somewhat more rapidly above than below 
the ambitus, so that a narrow, almost bare space is left near the apex 
of the test ; near the line of suture one of the secondary tubercles is 
often rather prominent. The poriferous zones vary somewhat in 
breadth, the arrangement of the pairs of pores in ares being in- 
constant. Hach compound pore-plate may carry five or six pairs of 
pores, and on each there is one rather large tubercle. 
The plates of the calycinal area form a narrow ring, and even the 
madreporite is not very prominent: the tuberculation is inconstant ; 
two of the radials touch the periproct, which is of an elongated 
oval form. The vent is excentric; round it are some very small 
plates, but the rest of the circumanal plates are rather large. 
The test may be of a purplish or pinkish hue ; the poriferous zones 
are generally of a lighter hue than the rest of the test, but appear 
to be somewhat depressed in consequence of the smaller size of the 
tubercles on than those to either side of them. 
Diameter of 
Diameter Height of ———- ait SN 
of test. test. Peristome. Calye. area. _Periproct. 
82 o7 24 15 9 
66°5 40 21 11:5 § 
58 36 20°5 9 
5 
48 30 18:5 85 3) 
