FROM THE CORAL RAG. 303 



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

 of the same size. 



Affinities and differences. — This urchin in its general fades bears so much resemblance 

 to H. gibberulus, 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 II. agariciformis, and by the shortness of the single inter- 

 ambulacrum from H. caudatus. 



Locality and Stratigrap/iical 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 ParJcinsoni, Sow., near Hampen, Gloucestershire, where it is associated 

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

 Hugi, Agass., Clypeus Plottii, Klein, Trigonia costata, Sow,, Pectin symmetricus, Morris, 

 Ammonites ParJcinsoni, 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 Pag. 



Hyboclypus stellatus, Desor. 



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



3 e serie, tome vii, p. 152. 



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



— marcou. D'Orbigny, Prodrome de Paleontologie, tome ii, p. 26. 



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

 II. canaliculars et H. Marcou, mais differant de Tun et de l'autre par ses ambulacres 

 posterieurs qui sont rectilignes au lieu d'etre arques. T. 76 (type du l'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. 



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