BRITISH FOSSILS. 



7 



Prof. Forbes, however, still referred to Goldfuss's species a specimen from the 

 Grey Chalk of Dover, presented to the Museum of Economic Geology, by E. H. 

 Bunbury, Esq., M.P. 



This specimen is circular, and measures 14 lines in diameter, by 6^ in height ; the 

 upper opening is pentangular, and 6 lines across ; the mouth only 4 lines, and very 

 deeply sunk ; the primary tubercles are more prominent than in D. Benettice, 

 diminishing in size below, but not much upwards ; the areolse are radiated ; the 

 interambulacral tubercles are 12 in each row, divided by two rows of irregular 

 granules, separating above and leaving bare channels ; these areas are bordered below 

 by two rows of accessory tubercles ; the ambulacral tubercles are like the others, in 

 two rows of 12 each, and nearly as large, converging above ; the pores are close 

 together above, but towards the circumference they are separated by conspicuous 

 tubercles, or groups of granules, which gives them a straggling appearance, and 

 makes them difficult of detection. 



A second example of this Diadema, presented to the British Museum by Daniel 

 Sharpe, Esq., has 14 tubercles in each row, and Mr. Bowerbank's example, re- 

 ferred to above, has 16-17 primary tubercles, which are consequently smaller 

 and more crowded. A specimen in Mr. Mackie's cabinet is more elevated, and 

 remarkably contracted at the base: it measures 13^ lines in diameter, and T\ in 

 height. 



Locality. — Chalk Marl, Dover. (Mus. P. Geol., Brit. Mus. &c.) 



12. D. Benettice, Forbes, Morris's Catalogue, 2nd edit. 1854. {Cidarites ornatus, 

 Goldf., Petr., t. 40. f. 10. ?) Desor, Synopsis, p. 12. 



Body circular, inflated, depressed ; lat. 14, alt. 6 lines (sp. maj.); apical disk large (154- 

 lines diam.), pentagonal ; oral opening small (4 lines), deeply sunk ; ambulacral tubercles 

 as large as the interambulacral, in two distinct rows of about 1 5 each, separated by a 

 double row of minute tubercles and granules ; interambulacral tubercles in two primary 

 rows of about 14 each, separated by a wide median space, unequally granulated, which 

 becomes smooth above, and bordered by similar spaces, in which a few small tubercles 

 are developed. The areolte are sometimes radiated. Pores in regular distinct rows ; those 

 of the circumference with a small tubercle between each pair. 



This species, abundant in the Upper Green Sand of Warminster, was dedicated by 

 Prof. Forbes to the late Miss Etheldreda Benett, of Norton House, authoress of 

 the "Catalogue of Wiltshire Fossils" (1831). In the first edition of Morris's 

 Catalogue it was recorded as D. ornatum, Goldf, at my suggestion ; and in the 

 second edition, both names appear for the one species. As we have no authentic 

 examples of D. ornatum^ it is impossible to say in what respect it differs. M. 

 Michelin has, however, communicated to Dr. Wright a specimen labelled " D. 

 ornatum, Goldf. — Cap la Heve," which is undistinguishable from the Warminster 

 specimens of D. Benettice. 

 Localities. — Upper Gp.een Sand, Warminster ; Durdle Cove, Dorset. 



13. D. Barretti, Woodw. 



Circular, depressed ; lat. 11, alt. 5 lines; pairs of pores in single file throughout ; 

 ambulacral tubercles as large as interambulacral, in 2 distinct rows of 12 each, 

 divided by a double row of granules margining the plates ; interambulacral tubercles 

 in 2 principal rows of 11-12 each, separated by 4 rows of granules, which partly 

 surround the tubercles of the circumference and 2 secondary rows of 8-9 rather 

 smaller tubercles ; base concave ; apical opening moderate, pentangular. 



Differs from " D. Benettia,'" Forbes, and from IJ. tenue, Ag., in the development of 

 secondary rows of interambulacral tubercles. 



Locality. — ^Upper Green Sand, Cambridge, (Coll. Brit. Mus., and of Jas. Carter, 

 Esq.) 



