FROM THE INFERIOR OOLITE. 199 



beautiful series of type specimens they have sent me for comparison, and which are 

 perfectly identical with our English forms. 



History. — First entered in the * Catalogue raisonne des Echinidcs ' of Agassiz and Desor 

 as Poli/cyphits nodulosus^ under the supposition that it was identical with Milnster's 

 species from Nattheira ; a more pentagonal form was afterwards figured by me in the 

 ' Annals of Natural History/ under the name of Arbacia nodulosa. M. Desor has the merit 

 of having shown that it is even generically distinct from the German urchin, which 

 has narrow zones and unigeminal pores ; whereas our species has wide zones, and the 

 pores in oblique trigeminal ranks. M. Desor has therefore described and figured it as a 

 distinct species, under the name Tolycyplais Normannus. 



PoLYCYPHUS Deslongchampsii, WriyU. PL XIII, fig. 5 a, h, c, d, e,f. 



PoLYCYPHUs Deslongchampsii. Wright, Annals and Magazine of Natural History, 2d series, 



vol. xiii, p. 1/9, pi. 12, fig. 4. 

 — — Morris, Catalogue of British Fossils ; additional species of 



Echinodermata. 



Test small, hemispherical, and circular ; ambulacral areas with two rows of large, and 

 two rows of smaller tubercles ; inter-ambulacral areas divided into lobes by a median 

 depression, and provided with two rows of large, and several rows of smaller tubercles, 

 the small tubercles often degenerating into granules ; basal tubercles large and prominent ; 

 apical disc prominent. 



Dimensions. — Height, seven twentieths of an inch ; transverse diameter, thirteen 

 twentieths of an inch. 



Description. — Amongst the many beautiful forms of Echinidjg found in the Oolitic 

 rocks, this pretty little species will bear comparison for neatness and symmetry with any 

 of the family to which it belongs. I first found a solitary specimen of this species about 

 four years ago, and since then have obtained an interesting series of difi'erent ages ; but it 

 is a very rare species. 



The ambulacral areas are one half the width of the inter-ambulacral (fig. 5 b, d) ; they 

 have two rows of tubercles set closely and regularly together on the extreme margins of 

 the areas (fig. bb,f); between these are two shorter, inner rows, which do not extend 

 more than two thirds the length ; at the base of the area ten large tubercles are disposed 



