FROM THE INFERIOR OOLITE. 303 



tubercular surface is crowded with small granules ; the tubercles of both areas are the 

 same size. 



Affinities and differences. — This urchin in its general /aczV^ bears so much resemblance 

 to H. gihherulus, Agass., that at one time I considered it a variety of that species; but the 

 absence of the gibbous crest, the fulness of the anterior border, the straightness of 

 the anterior ambulacra, the form and direction of the posterior pair, together with the 

 difference observed in the shape of the longitudinal valley, have induced me to separate it 

 from that species under the name H. ovalis. By its oval shape and elongated apical disc 

 it is distinguished from 11. agariciformis, and by the shortness of the single inter- 

 ambulacrum from H. caudatus. 



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

 marly fossiliferous vein which traverses the upper ragstones of the Inferior Oolite, in the 

 zone of Ammonites Parkinsoni, Sow., near Hampen, Gloucestershire, where it is associated 

 with Holectypus dejnessus, Leske, H. hemisphcericus, Desor, Pedina rotata, Wright, Clypeus 

 Iluyi, Agass., Clypeus Plottii, Klein, Triyonia costata, Sow., Pectin symmetricus, Morris, 

 Ammonites Parlcinsoni, Sow. I have found one specimen in the Trigonia bed at Cold 

 Comfort, where it was associated with the large Perna isognomonoides, Stahl. 



B. Species from the Coral Pay. 

 Hyboclypus stellatus, Desor. 



Hyboclypus stellatus. Desor, Catalogue raisonne Annales des Sciences Naturelles, 



3° serie, tome vii, p. 152. 

 — — Desor, Synopsis des Echinides Fossiles, p. 193. 



This urchin is described by M. Desor as " Espcce intermediaire par sa forme, entre les 

 //. canaliculatus et H. marcon, mais differant de Fun et de I'autre par ses ambulacres 

 posterieurs qui sont rectilignus an lieu d'etre arques. T. 76 (type du I'espece). 



" Formation. — Corallien du Wiltshire. Rare. 



" Collection. — M. Le Viscomte d'Archiac." 



I only know this species from the above notice, as I have never been so fortunate as 

 to see a specimen of it in any of the collections of Coral-rag urchins which I have 

 examined. 



40 



