mity. The spine, which gives name to the species, runs down from 

 the vertex and along the narrower end, and becomes attached to the 

 higher edge of the anus. Plate II. Fig. 4, is a species from the Kentish 

 chalk-pits. 



E. ovatus, Lesk. Galea wagrica, vert ice ?mda, Klein, differs from the 

 former species in being more depressed in its circumference, being of a 

 rounder oval ; and in being without the -crest- like ridge which runs along 

 the back of the other species. Another species, Echinocorytes quaterradia- 

 tus, has been formed from an echinite figured and described by Melle, 

 Tab. i.' Fig. 7 : but I suspect the absence of the fifth ray has pro- 

 ceeded from the omission of the engraver, since, in the remarks on this 

 fossil which are made by Melle, at some length, this remarkable cha- 

 racter is not noticed. 



Among the smaller echinocorytes, most of which are mere nuclei, certain 

 particulars are observable, which, though hardly sufficient to distinguish 

 them as varieties, still deserve notice. A variety is marked by Leske, 

 Tab. xvi. c. D. Klein, Galeolapapillosa; in which, as he observes, the papillae 

 evidently result from the silicious matter which filled the foramina of the 

 shell still continuing, whilst the shell which surrounded them is re- 

 moved. Another, Tab. xvn. a. b. Klein, is named G. undosa, from the 

 waving lines on its surface, formed by the silicious matter having insi- 

 nuated itself between the edges of the plates forming the shell. 



Part of a remarkable cast of a galeated echinite is shown Plate II. 

 Fig. 9, said to be from France. Although this fossil is hollow, and 

 retains such strong markings of the shell, it can still be only considered 

 as a cast. Its substance appears to be pyrites of iron, which has suf- 

 fered some decomposition, and has been since frosted over with minute 

 quartz crystals. Its matrix appears to have been chalk, some of this 

 substance being yet adherent to it on several parts. Its formation appears 

 to have taken place, by the shell becoming imperfectly invested, both on 

 the in and the outer side, with the pyrites, which then obtained a par- 



