134 INVERTEBKATA. 



Some occasional and exceptional spines occur amongst some oi 

 the undermentioned species of Cidaris, which are undistinguishablej 

 from the Upware spines. Bat these latter are the proper type of 

 the species, and not exceptional, as is proved by the constancy of] 

 their character in all the known specimens. I have not been able] 

 therefore to identify them with any known species. 



G. verticillata (Stoppain) differs in that its thorns are grouped] 

 in verticals. In G. spinigera the spines are more slender, and are 

 usually curved (Cotteau), the thorns also being longer and morej 

 spine-like. 



It is nearest to G. spinosa, Agassiz, of the Jura, Terr, a Chailles' 

 at Fringeli, found also in the Jurassic of Normandy and N. 

 Germany. "Un espece tres voisine, raais cependant specifique- 

 ment differente, provenant de I'argile de Speeton, est figuree dans 

 Phillips, Geol. Yorkshire, t. ii., f. 3." This figure shews the thorns 

 arranged, somewhat irregularly, in zones. 



The thorny spines of G. muricata in the Hils Conglomerat vary 

 much as seen in the Gottingen Museum, but they are distinguished 

 from our Upware species by having the interspaces between the 

 thorns muricated. 



Some forms of the G. variabilis (Dunker and Koch) agree very 

 well with ours, but the spine is sharper, and we do not find any of 

 the typical forms of this species at Upware. Other thorny spines 

 occur in the Cretaceous of Rugen (Desor), and in the Kimmeridge 

 Clay of Ely (Woodwardian Museum), 



A single interambulacral plate in the Woodwardian Museum, 

 from Upware, may have belonged to the same Urchin. It .does 

 not agree with Coster's figure of what he believes is the plate of 

 G. spinifera. It is transversely oblong, densely granulated, with 

 large areole, wide and rather prominent boss, with coarsely crenu- 

 lated summit. 



Localities. Upware, Brickhill, Farringdon (?), Godalming. 



Cidaris ? sp. 



The pyramid of jaws (alveoli) of a large Urchin, measuring one 

 inch in height and breadth. 



Locality. Upware (Coll. Mr J. F. Walker). 



