136 



NOTES 



On Foreign Jurassic species or the genus PSEUDODIADEMA nearly allied to 

 British forms, but which have not yet been found in the English Oolites. 



A. Pores unigeminal in the upper part of the zones ; no secondary tubercles. 



Pseudodiadema subcomplanatum, d 'Orbigng. Prodrome de Paleontologie, p. 319. 



Test small, depressed, pentagonal ; tubercles of both areas at the base, and equator of 

 the test proportionately large, prominent, and equal sized ; ambulacra prominent, with 

 eight or nine tubercles in each row, nearly as large, but more crowded together at the 

 base and equator ; diminishing more rapidly in size in the upper part of the area than 

 those of the inter-ambulacra. Inter-ambulacral areas with eight rows of large prominent 

 primary tubercles, and four small secondary ones on their zonal sides at the base ; miliary 

 zone narrow, with two rows of granules ; nearly related to P. complanatum, Agass., and 

 to P. depressum, Agass. It differs from the former in having a much larger mouth- 

 opening, and from the latter in having larger tubercles, a narrower miliary zone, and four 

 small secondary tubercles at the base. 



Dimensions. — Height, three tenths of an inch ; transverse diameter, four fifths of an 

 inch. 



Formation. — Grande Oolite, ll e etage Bathonien, de Ranville, Luc (Calvados). 



Collections. — Deslongchamps, Michelin, d'Orbigny, my Cabinet. 



Pseudodiadema complanatum, Agassiz. Syn. Biadema compianatum, Agass., Echinod. 



Suisse, part ii, tab. 17, fig. 31 — 35. 



Test small, very much compressed; the ambulacral are smaller than the inter- 

 ambulacral tubercles, and they diminish more rapidly in size at the upper surface, but in 



