PROM THE GREAT OOLITE. 371 



late ; the pores at no point arc at any great distance apart ; the anal valley in both species 

 extends from the apical disc to the margin, but in Chjpeus Michelini it is more expanded 

 below and deeper above than in Chjpeus Mullen. 



I have now before me Clypeus angusiiporus, Ag., from a coarse Oolitic rock (Brad- 

 fordien ?) near Metz, collected by M. Terquem, and kindly sent me by M. De Loriere ; this 

 urchin appears to be a variety of Chjpeus Plotii ; from which C. Michelini differs in many 

 ' particulars. In the French urchin the apical disc is excentral, the anal valley wide 

 above and not much expanded below, the ambulacral areas are narrow, and the test 

 declines gradually from the vertex to the anterior border, which forms a rather acute angle J 

 the base is undulated, and the mouth-opening nearly central ; these characters distin- 

 guish it from our urchin. 



Chjpeus Michelini differs so widely from all the varieties of Clypeus Plotii with 

 which I am acquainted, that it cannot possibly be mistaken for either of them, if proper 

 care be taken when a comparison is made between them. 



Locality and Stratigraphical position. — I have collected this species chiefly from the 

 Freestone beds of the Inferior Oolite at Wallsquarry and Nailsworth, Gloucestershire ; 

 the specimens figured in PI. XXX, were cut out of the centre of a block of building 

 stone ; the Oolitic grains were imbedded in the plates of the test, and have in some 

 measure injured their surface. I found two small specimens in the zone of Ammonites 

 Humphriesianus, in a sandy bed of this middle division of the Inferior Oolite at Cleeve 

 Hill, near Cheltenham, where it was associated with Ammonites Brongniarti, Sow., 

 Am. Humphriesianus, Sow., Am. Brocchii, Sow. Mr. Reed, of York, collected several 

 specimens germinans from the Inferior Oolite at Whitwell, Yorkshire ; one of these, kindly 

 given me by that gentleman, I have figured in PL XXVI, fig. 2. It was associated with 

 Stomechiyms germinans, Phil., Trigonia costata, Sow., Gervillia Hartmanni, Miinst., and 

 other Inferior Oolite shells. 



B. Species from the Great Oolite. 

 Clypeus Mulleri, Wright. PI. XXXIII, figs. 1, 2, 3, 4, 5, 6. 



NrcLEOLiTES SoLODTJRiNUs. Wright, Ann. and Mag. of Nat. Hist., 2d ser., vol. ix, p. 305, 



1851. 



— — Forbes, in Morris's Cat. of Brit. Foss., 2d ed., p. 84, 1854. 



— — Wright, Report on Brit. Ool. Echinodermata, Brit. Assoc. 



Report, 1857. 



Test oblong, posterior border much produced, deflected, and truncated ; ambulacral areas 

 largely petaloidal, with their apices closely approximated ; apical disc and vertex excentral 



