﻿FROM THE MEDIAL CHALK. 



221 



the disc, supporting on its surface the raadreporiform body. The five ocular plates are 

 very small cordate bodies, wedged between the ovarials (PI. LII, fig. e, PI. LIII, 2/). 

 The surface of all the discal elements is covered with microscopic granulets. 



Affinities and Differences. — This species resembles some globular varieties of E. 

 vulgaris, and is often grouped with these in collections. It has a more globular form 

 and is less elongated, the ambitus is more rounded, and the vent opens higher up in the 

 border. It differs from E. castanea in the general outline of the test by being more 

 globular, and elevated with a more convex dorsal surface. The same characters dis- 

 tinguish this species from E. conicus, from which, however, it further differs in having 

 smaller tubercles, and a more microscope form of granulation. It differs from E. 

 abbreviates in the general form of the test, and in having much smoother plates, from the 

 smallness of its tubercles ; those in E. abbreviates being larger, and surrounded by a 

 more prominent granulation ; the vent likewise is more inferior, and the single inter- 

 ambulacrum neither tumid nor rostrated as in this species. 



Locality and Strati (jraphical Position. — I collected my large specimen from the Lower 

 Chalk, near Lewes, in Sussex ; it is found in the same stratum at Charing, in Kent, and 

 in the Lower or Hard Chalk at Feltwell Marborough, in Norfolk, it is therefore a 

 fossil characteristic of the Lower Chalk, and in this respect differs from E. conicus, E. 

 globulus, and E. abbreviates, which all appertain to the Medial and Upper Chalk. The Rev. 

 T. Wiltshire, F.G.S., has collected this species in the Lower Chalk, near Folkestone, from a 

 stratum fifteen feet above the bed of hard gritty chalk, but never in the gritty chalk itself. 



b. — Species from the Medial Chalk. 



Echinoconus conicus, Breynins, 1732. PI. XLIX, figs. 2, 3, 4 ; PI. L, figs. 1 — 6. 



Echinocon'us ver£: conicus, Breynius. Scbed. de Echinis, p. 57, pi. iii, fig. 12, 



1732. 



Klein. Natur. dispositio Echinoderm., p. 24, tab. xiii, 

 a, b, 1734. 



Bourguet. Trait, des Petrif.,p. 77, pi. liii, fig. 360, 1742. 

 Leske. Apud Klein, p. 1C2, tab. xiii, a, b, 1778. 

 Gmelin. Systema Naturae, p. 3181, No. 46, 1789. 

 Bruguiiire. Tab. Encycl. Atlas, pi. clii, figs. 5, 6, 1/91. 

 Parkinson. Organic Remains, vol. iii, pi. ii, figs. 10, 11, 

 1811. 



Lamarck. Animaux sans Vert., t. iii, p. 20, 1816. 

 Defrance. Die. Sci. Nat., t. xviii, p. 86, 1820. 

 Brongniart . Foss. envir. de Paris, p. 631, pi. 1, fig. 12, 



coxulus albogalerus, 



echixite coxoide, 

 coxulus albogalerus, 

 Echinus — 



Conulus — 



Galerites — 



