480 RADIATA. PLEUROCYSTI. Spatangus. 



Gen. IV. SPATANGUS. — 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, Mluller, Zool. Dan. iii. p. I7. 



tab. xci. f. 1-4 S. pusillus, Leske, ap. Klun. p. 230. t. xxiv. c, d, e. 



tab. xxxviii. 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, rhoraboidal, with two pores in the lateral angles ; primary 

 spines few, on rough tubercles ; spaces between the pairs ot pores in the 

 avenues smooth. 



7. S. ovatus. — Groove between the mouth and vertex obso- 

 lete. 



Flem. Wern. Mem. v. 287- t. C, lower figure. I.eske 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 pi'oduced ; vent transversely ovate, the inclosed space beneath cordi- 

 torm, with smgle lateral pores ; primary spines, supported on tubercles, with 

 a central ligament, and surrounded by a monilitbrm 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 sidjquadrangidar space on the vertex. The 

 pairs of pores in the avenues connected by transverse lines. 

 Compression at the vent oblique. 



8. S. purpureus. — Vertex sloping to the margin. 



Muller^ Zool. Dan. i. p. 5. tab. vi. 1-5. copied by Leske, tab. xliii. f. 3-5. 



with a good description Echinus lacunosus, Penn. Br. Zool. iv. p. C9. 



tab. XXXV. f. 7fi On the English coast, rare — Frith of Forth, com- 

 mon. 



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