366 CLYPEUS 



From Clypeiis mhulatus. Young, it is distinguished by its orbicular outline and anal valley ; 

 in that urchin the outline is oblong, and the anal valley quite short and marginal. The 

 height and convexity of Clypeus Agassizii, Wr., with its shallow anal valley and inflated 

 test, prevent the possibility of mistaking Clypeus Plotii, Kl., for that urchin, which re- 

 places it in some of those regions where the latter is absent. 



Locality and Stratiyraphical position. — The metropolis of Clypeus Plotii is the Trigonia 

 grit of the Inferior Oolite, in the zone of Ammonites Parkinsoni; it is extremely 

 abundant in some localities, but rare in others ; over the central parts of the Cotteswold 

 Hills it is found in great numbers ; where its bed crops out at the surface, as near 

 Naunton Inn, a cartload of weathered Clypei might sometimes be collected. My best 

 specimens were obtained from near Stow-in-the-Wold. I have likewise collected beautiful 

 examples at Rodborough Hill, Scar Hill, Shurdington Hill, Leckhampton Hill, Cleeve 

 Hill, and at Cubberley, Cowley Wood, Pen Hill, Little Rissington, Adlestrop, Northleach, 

 and Hampen, Gloucestershire ; in the same zone near Burford, and Sarsden, and in the 

 Stonesfield Slate at Stonesfield, Oxon. Mr. Lycett obtained one specimen from the 

 Fuller's-earth, at Minchinhampton Common ; it is found likewise in the Great Oolite at 

 Minchinhampton, Gloucestershire ; Kiddington, Oxon ; and Kingsthorp, Northampton. 

 Mr. Macneil, after many years' collecting, found only two specimens in the Cornbrash 

 at Trowbridge, Wilts, both of which are now in my cabinet. 



The Foreign distribution of this species, according to M. Desor, is "Oolite vesulienne du 

 Kornberg pies Frick et Buren pros Gensingen (Argovie), Muttcnz (Bale), Porrentruy, 

 Plasne pres Poligny, St, Andre pres Salins. 



"Grande Oolite deBoulogne-sur-Mer, Chayal (Ardennes), Montanville, Flincy (Meuse), 

 Noviant, Besangon." 



Clypeus altus, M'Coy. PI. XXVII, fig. 1 a, b, c, d, e,f. 



Clypeus altus. M'Coy, Ann. and Mag. of Nat. Hist. 2d ser., vol. ii, p. 417, 1848. 



NucLEOLiTES ALTUS. Forbes, in Morris's Catalog, of Brit. Foss., 2d ed., p. 83, 1854. 



Clypeus Davousttanus. Dcsor, Synopsis des Echinides Fossiles, p. 55, 1855. 



— ALTUS. Wright, Stratigraph. Distrib. Ool. Echinoder., British Association 



Reports, 1856. 



— Davoustianus. Cotteau, in Davoust, Note sur les foss. spec, de la Sarthe, p. 7, 



1856. 



— — Cotteau, Note sur quelques Oursins de la Sarthe, Bull, de Geol. 



Soc. de France, 2° ser., t. xiii, p. 650, 1856. 



— — Cotteau and Triger, Echinides du depart, de la Sarthe, pi. xii, 



figs. 1—7, p. 62, 1858. 



Test sub-circular, broader than long, upper surface evenly convex, high, and sometimes 

 sub-conical ; base concave, very much undulated, from the extreme tumidity of the basal 



