2 



BRITISH FOSSILS. 



Agassiz and Desor (1846), Cat. Eaisonne, Ann. Sc. I^at. 3rd series, 

 vol. vi. p. 365. multigranularis^ Cotteau (1850), Etudes Ech. Foss. de 

 I'Yonne, p. 63. tab. 7. fig. 6-8. 



Yar. 7, serialisyjig. 5. — Depressus granulosus, tuberculis primariis amhula- 

 cralibus minoribus, secundariis insuper rarissimis, ad later a inter ambula- 

 crorumin serie unica dispositis ; fasciis pororum latis ; poris parallelis : bast 

 subconvexa; ore angulis obtusiusculis. — E. serialise Agassiz, Ech. Foss. 

 Suisses, 1. c. fig. 10-12. Wright, Ann. and Mag. Nat. Hist., 1. c. pi. 13. 

 fig. 2. Ag. and Desor, 1. c. p. 366. 



Vajs. I, Forbesii,Jig. 6. — Rotundus seu pentagonus granulosus ; tuberculis 

 primariis conspicuis, ambulacralibus minoribus irregularibus : fasciis poro- 

 rum angustis, seriebus usque ad orem valde obliquis. 



At first sight it would appear very unlikely that the forms here 

 figured should be all of one species, or that either of them could be 

 identified with the much rougher and more globose Echinus, which 

 Agassiz calls " sans contredit Tun des plus beaux oursins connus." 



The comparison of the several English specimens, however, with 

 one another, and with the foreign types, convinced both Prof. 

 Forbes and Dr. Wright that they were identical, and as such they 

 have been quoted in the second edition of Morris's Catalogue. 



Agassiz has placed this fossil species and several others allied to 

 it with his first section of the genus, in which the pores are arranged 

 in triple oblique (not arched) rows, and in which the buccal mem- 

 brane, instead of being covered all over with calcareous plates, has 

 only five escutcheon-like plates disposed around the mouth. The 

 margin of the latter is deeply notched, and in these notches lie 

 those curious branched processes which Prof Forbes counted ana- 

 logous to the oral tentacula of the Holothurice (Prof Miiller terms 

 them 'tree-like gills'). 



Description. — -The variety germinanSj forming the principal sub 

 ject of our plate, requires more particular notice. It is conical and 

 elevated above, flattened and even excavated below. Diameter of 

 the largest English specimen, 8 inches, its height 2 inches. The 

 outline, looking from above, is subpentagonal rather than rounded ; 

 the ambulacral aresD being rather more convex than the others, 

 which are depressed along their median line. 



The breadth of the interambulacral spaces is 2 J times that of the 

 ambulacra at the widest part ; the number of plates in a row is 

 twenty-nine, of which eight are basal, and, in English specimens, 

 bear three or four very large primary tubercles, with a few secon- 

 daries at the outer angles. At the turn of the margin these all 

 <lisappear, and the upper plates only bear each a single primary, 



