APPENDIX I. 



SUMMAEY* OF THE EEITISH LIASSIC AND OOLITIC 

 ECHINOIDEA, ASTEEOIDEA, AND OPHIUEOIDEA, 



Described in Volumes I and II of the Oolitic EcJiinodermata. 



Order I— ECHINOIDEA, Wrij^/d (Vol. I, pp. 4, 6—16). 



Body-shell (test) spheroidal, oval, cordate, or depressed, without arms, furnished with 

 a distinct mouth {oral opening), whose border {peristome) is sometimes simple, some- 

 times lobed, always on the under side, and generally armed with five calcareous sets of 

 plates {jaics). Anal opening variously situated on the upper or under side, or on the 

 marginal border. Body enclosed in a shell {test), composed usually of twenty, sometimes 

 of more than twenty (as in the family of the Palaeozoic FerischoecJiinidce), columns of 

 calcareous plates, forming, in either case, ten areas. Five of the areas {ambulacral) 

 containing each two rows of apertures {poriferous zones) for the passage (in the living 

 state) of retractile suckers {ambulacral tubes). The other five areas {inter amhulacral) 

 destitute of sucker-pores. Ambulacral pores disposed in single pairs {unifjeminal), 

 double {])igeminal), or triple oblique {trigeminal). Ambulacral pore-columns {areas) 

 sometimes continuous from the peristome to the summit {complete), sometimes confined 

 to the upper surface of the test {interrupted)., or forming re-entering ciu'ves {petaloid). 

 Surface of test studded with tubercles {jjrimarg, secondary, and miliary), possessing 

 spines of various forms and dimensions. Spines articulated on the rounded upper part 

 of a tubercle {mamelon), which rises from a conical process {hosi). Base of tubercle 

 surrounded by a round, oval, smooth, excavated space {areola or scrobicule). Summit of 

 test marked by an apical disc, composed generally of five genital and five ocular plates, 

 usually in contact and central. Cutaneous surface of shell, especially near the mouth, 

 bearing small tripartite, pincer-like bodies {pedicellarice), placed on a short stalk, whose 

 lower portion encloses a calcareous nucleus. Pedicellariae capable (in living state) of 

 seizing small bodies and passing them from one to the other. Movement of the animal 

 effected by the motion of the spines and the ambulacral tubes. 



The EcHiNoiDEA (including the Perischocchiiiida)) range from the Silurian to the 



* Compiled by the Eev. T. Wiltshire, M.A., F.G.S., Hou. Sec. Pal. Soc. 



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