480 
RADIATA. PLEUROCYSTI. 
Spatangus. 
Gen. IV. SPAT ANGUS. — Avenues of pores circumscribed. 
A groove or band extends from the mouth, which is trans- 
versely lunate, to the four orifices of the oviducts in the 
vertex. Anus in a compression in the margin, with a cir- 
cumscribed space immediately underneath. 
a. A suhquadrangular space on the vertex^ containing the orifices 
of the oviducts, inclosed by a narrow band. The pairs of 
pores in the avenues not connected by lines. Compression 
at the vent vertical. 
6 . S. cordatus. — Mermaids’ Heads; Sea-eggs. — A deep groove 
on the margin between the mouth and vertex. 
Echinus spatagus, Merret^ p. 192., Depressed cordate sea-egg. Bor* 
Corn. p. 278. tab. xxviii. f. 28 — E. c. Penn. Brit. Zool. iv. p. 69. 
t. xxxiv. f. 75 — Spatagus flavescens, Muller^ Zool. Dan. iii. p. 17 . 
tab. xci. f. 1-4. — S. pusillus, LesTce^ ap. Klun. p. 230. t. xxiv. c, d, e. 
tab. xxxviiL 5. — Common in all the sandy bays. 
Length about two inches ; vertex hollowed ; oviducts in pairs, diverging, 
with an intermediate punctured space ; vent vertically ovate ; the inclosed 
spaces, beneath, rhomboidal, with two pores in the lateral angles ; primary 
spines few, on rough tubercles ; spaces between the pairs of pores in the 
avenues smooth. 
7. S. ovatus. — Groove between the mouth and vertex obso- 
lete. 
Flem. Wern. Mem. v. 287- t. 6., lower figure. Leske ap. Kl. p. 252. 
tab. xlix. f. 12, 13 — Scottish coast, rare. 
Diameter an inch and a quarter, purple ; vertex nearly even ; oviducts 
approximate, with the punctured space behind, and the spines covering this 
place produced ; vent transversely ovate, the inclosed space beneath cordi- 
form, with single lateral pores ; primary spines, supported on tubercles, with 
a central ligament, and surrounded by a moniliform ring ; the spaces be- 
tween the pairs of pores in the avenues rough. 
This species differs so much from the preceding in so many characters, as 
to leave no room to doubt its claim to rank as a distinct species. Doubts, 
however, may be entertained as to the propriety of the synonym prefixed. 
This species is more globular than expressed in Leske’s figure, and the line 
from the oviducts to the mouth, instead of being carinate, is flat- A single 
specimen of this species occurred to me in 1809 in Zetland. In 1825, Dr 
Coldstream found another on Leith sands. 
b. Destitute of a suhquadrangular space on the ^vertex. The 
pairs of pores in the avenues connected by transverse lines. 
Compression at the vent oblique. 
8 . purpureus. — Vertex sloping to the margin. 
Muller., Zool. Dan. i. p. 5. tab. vi. 1-5. copied by Leslie., tab. xliii. f. 3-5. 
with a good description — Echinus lacunosus, Penn. Br. Zool. iv. p. 69. 
tab. XXXV. f. 78 — -On the English coast, rare — Frith of Forth, com- 
mon. 
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