ECHINOOYAMUS. 11 



fossil example measured five twelfths of an inch in length. The breadth and height vary 

 according to the variety. 



2. Echinocyamus Suffolciencis. Plate I, fig. 16. 



Fibularia Suffolciencis, Agassiz. Prod., p. 188. 



— — Desmoulins. Tab. Syn., p. 244. 



Echinocyamus Suffolciencis, Agassiz. Monog. des Scutelles, p. 129, tab. xxvii, 



figs. 9—13. 

 — — Agassis and Desor. Ann. Sc. Nat., 3d series, vol. vii, 



fig. 141. 



The distinguishing features of this species are its compressed margin and the sub- 

 marginal position of the very small vent. The tubercles of its surface, though coarse 

 and conspicuous, and similarly set in deep areolae, are slightly smaller than those of 

 E. pusillus. 



There are two well-marked varieties : — 



a. The test of this form is broadly sub-pentagonal, much depressed, flattened out 

 towards the margins, sub-rostrated anteriorly, hollowed out slightly beneath, and has the 

 mouth slightly sub-pentagonal. This is the larger variety. It measures as much as 

 four twelfths of an inch in length by three tenths in breadth, and one eighth in height. 



b. The test is ovate or elongate, rather more tumid, with a round and proportionately 

 larger mouth. The largest specimen observed, measures three twelfths of an inch in 

 length by two tenths in breadth and one twelfth in height. 



Both are found in the Red Crag of Walton on the Naze. 



The description given by Agassiz does not touch upon the remarkable position of the 

 vent, and is very insufficient. He states, that it comes very near E. pusillus, but differs 

 in its more depressed, and broader, and more circular shape. He notices the smaller 

 tubercles. His figure is not characteristic, and apt to mislead. It represents a specimen 

 of the smaller variety, but the position of the vent is exhibited much too far from the 

 margin. Since this distinguished naturalist named the specimens in Mr. Wood's cabinet, 

 there can be no mistake about which he meant. I mention this, because the name 

 Suffolciencis seems to be applied to another species in the ' Catalogue of British Fossils.' 



3. Echinocyamus hispidulus. Plate I, fig. 14, a, b, and c. 



This very distinct species is more or less sub-orbicular, or sub-pentagonal, much de- 

 pressed, variably convex above, usually tumid at the margins, and slightly concave in the 

 region of the mouth. The entire surface is covered with very minute tubercles and 

 granules, so as to give it a hispid appearance to the naked eye. The boundaries of the 

 plates are indicated by very distinct groovings. The ambulacral pores are very indis- 



