FROM THE INFERIOR OOLITE. 155 



The base is flattened, but the mouth opening is unfortunately concealed in the only 

 two specimens I have found. 



Affinities and differences. — I regarded this urchin, at first sight, as a young form of 

 H. tetragramma, but the spaced-out arrangement of the ambulacral tubercles, the inflation 

 of the sides of the test, and the presence of only two rows of tubercles in the inter- 

 ambulacra, show that it is quite distinct from that species. It is so entirely different from 

 H. perforatus and H. Bakeri, that it cannot be mistaken for either of them. 



Locality and Stratigraphical position. — I collected this urchin in the Pea Grit at 

 Crickley Hill, with the former. It must be rare, as I only know two examples of the 

 species, which I dedicate to my friend G. R. Waterhouse, Esq., F.Z.S., of the British 

 Museum, well known by bis valuable contributions to zoological literature, and by the 

 kindness and urbanity of his manner to all who seek information in that department 

 of the wreat national collection committed to his care. 



