4*78 RADIATA. ANOCYSTI. Echinus. 



tween the pores, consist each of a large and small tubercle, supporting small 

 spines, and scattered eminences to which the articulated bodies adhere, and 

 two pores. The five bones of the pelvis are subquadrangular, from the ring 

 of the vent, and, externally, are wedged in by fine subtriangular costce. 



EXTINCT SPECIES. 



1. C. Parkinsoni — The tubercles immediately above the margin the lar- 

 gest; the small compartments prominent. — Park. Org. Rem. iii. 10. t. i. f. 4, 

 5-8. — Lower Oolite. 



2. C papillata. — Body depressed ; each compartments with two rows of 

 tubercles, encircled by a distinct groove at the base — Park. Org. Hem. iii. 

 t. 1. f. 9 — Mant. Geol. 189. t. xvii. f. 18.— In Chalk and Oolite. 



3. C. intermedia — Lesser compartments half the width of the larger ones ; 

 tubercles crenulated at the base — Echinita, Park. Org. Rem. iii. 13. t. i. f. 6. 

 — Oolite. 



4. C. Urii — Single plates only observed ; tubercle with a double ring, the 

 margin of the plate granulated ; spines finely striated longitudinally, and 

 prickly towards the extremity. I have found, adjacent, what appears to be 

 one of the teeth. — Echinus, Ure, Ruth. 318. t. xvi. f. 7, 8. — Carboniferous 

 Limestone. 



Many more species are indistinctly referred to by Plott, Lister, Luid, and 

 Parkinson. 



Gen. II. ECHINUS. Sea-Urchin. — Tubercles and spines 

 destitute of the central connecting ligament. 

 In this genus the primary spines are more numerous, and 

 produced ; the avenues of pores are separated by larger 

 tubercular spaces, approaching at each end. 



* Three double rows of pores in each avenue ; the ring round 

 the vent formed by the plates of the pelvis. 



2. E. esculentus. — Plates covered with numerous nearly equal 

 tubercles. 



Merret's Pin. 192. List. An. Ang. 169. tab. iii. f. 18. Sib. Scot. ii. 3- 

 p. 26- — Borl. Corn. p. 278. tab. xxviii. 27. Monro, Phys. Fishes, p. 66- 

 tab. xliii. and xliv. Penn. Br. Zool. iv. p. 67. tab. xxxiv f. 74- Cor- 

 diner's Ruins, No. xiii — Found on rocks at low tides, common. 



This species varies considerably in shape and colour. The avenues of the 

 pores have waved transverse grooves, and a few scattered tubercles. In each 

 compartment there are two rows of primary tubercles, with numerous others, 

 of different sizes, covering the whole surface. A series of 10 tuberculated 

 plates surrounding the margin of the mouth, each with a central extensile 

 sucker. 



3. E. miliaris. — Plates with a single large, and a few small, 

 tubercles. 



Cidaris miliaris saxatilis, Leske ap. Klun. p. 82. tab. ii. A, B, C, D. xxxi, 

 A, D. xxxviii. 2, 3 — E. m. Flem. Mem. Wern. ii. p. 246— From Zet- 

 land, in deep water. 



