FROM THE CORALLINE OOLITE. 353 



specimens are those which occur in the large Freestone quarry at the east of the town. 

 C. W. Strickland, Esq., has obtained it in his quarry at Hildenley, near Malton, where it is 

 associated with Hemicidaris intermedia, Flem., Cidaris Jlori(jemma, Phil., Pseudo-diadema 

 hemispharicum, Agas., Collyrites bicordata, Leske, Fygurus pentagonalis, Phil., and 

 Nmleolites scutatus, Lamk. 



D. — Species from the Portland Oolite. 



EcHiNOBRissus Brodiei, Wright, nov. sp. PI. XXXV, fig. 1 a, b, c, d, e. 



Test elongated, much depressed, nearly as broad before as behind ; anterior border 

 roimded ; posterior border angular ; anal valley wide, short, limited to the lower half of 

 the inter-ambulacrum ; apical disc small, nearly central ; poriferous zones slightly 

 petaloidal ; base undulated, from the convexity of the inter-ambulacra ; mouth-opening 

 large, excentral, pentagonal, oblique, situated near the anterior border ; inter-ambulacrum 

 produced, recurved, and truncated posteriorly. 



Dimensions. — Antero-posterior diameter, one inch ; transverse diameter, nine tenths of 

 an inch ; height, four tenths of an inch. 



Description. — Urchins are so extremely rare in the Portland Oolite of England, that 

 the discovery of this specimen in that formation at Brill enables me to give a figure of a 

 nucleolite, of which I had formerly observed fragments in the same formation at Portland. 

 The test is unfortunately not well preserved in the Brill urchins, the matrix having adhered so 

 firmly to the test of the largest specimen that the surface could only be exposed by the use of 

 dilute acid, a process which at all times destroys the fine sculpture of the shell, and ought 

 never to be employed in cleaning Echinoderms but as a " dernier resort " for disclosing 

 structure in doubtful cases. The shell is elongated, a little wider behind than before, 

 the anterior border is rounded, and the posterior angular. The upper surface is much 

 depressed and uniformly convex, forming regular curves in the length and width (fig 1 c,d). 



The small apical disc occupies the vertex, which is anteriorly excentral ; its elements 

 unfortunately are concealed by some closely adherent matrix, which cannot be removed. 



The ambulacral areas are nearly all of the same width ; the poriferous zones are 

 narrowly petaloid, and both rows of holes are about the same size. 



The inter-ambulacral areas are of unequal width ; the anterior pair are the narrowest, 

 the posterior pair the widest, and the single area of intermediate width ; they are all 

 uniformly convex, and covered with very small tubercles ; the sides of the test are much 

 depressed, and form an angle of about 25° with the base ; the margin is rounded and 

 flattened before, and gradually expands to within the eighth of an inch of the postero- 



