206 STOMECHINUS. 



and the minute eye-holes appear like slits near the border; the vent is transversely 

 oblong, or has sometimes an irregular form (PL XIV, fig. 1 a) . 



The spines are small, delicate, and subulate, but are very seldom found in connection 

 with the tubercles. I have seen them twice when cleaning specimens, but unfortunately 

 they have fallen off in drying. 



Affinities and differences. — This is the true Echinus germinans, Phillips. Through the 

 kindness of Mr. Reed, of York, I possess two specimens of the type urchin, collected by 

 him at Whitwell, which I have critically compared with our specimens, and found them to 

 be identical. This species is certainly distinct from Echinus perlatus, Desmarest, which 

 has smaller and more numerous tubercles in the inter-ambulacra, narrower poriferous 

 zones, and wider ambulacra, than Stomechinus germinans. 



It differs from Stomechinus intermedius (PL XIV, fig. 2), which is considered by some 

 to be a mere variety of St. germinans, in having a more elevated and conoidal test, larger 

 tubercles, narrower and more prominent ambulacra, the apical disc more excentral, the 

 marginal angle more acute, the mouth opening larger, and the notches wider, with deeper 

 incisions ; but the two forms are unquestionably most nearly allied, and it is only when 

 placed side by side, and closely compared, that the differences become evident. 



It differs from Stomechinus bigranularis (PL XIV, fig. 3) in all the structural details 

 already referred to, in the comparison with St. intermedius ; but in addition to these, the 

 globose test, with its inflated sides and convex base, so characteristic of St. bigranularis, 

 added to the small mouth opening which this species possesses, enables us to distinguish 

 it readily from St. germinans ; as I shall have to return to these affinities and differences 

 when treating of both forms, I reserve further details until the respective species are the 

 subject of our special study. 



Locality and Stratigraphical position. — I have collected this species in the Pea-grit of 

 Leckhampton, Birdlip, and Crickley Hills, and it is found in the freestone beds of the 

 Inferior Oolite at Nailsworth and Wallsquarry, Gloucestershire. In Yorkshire it is 

 collected from the freestone beds of the Inferior Oolite at Whitwell, near Castle Howard. 

 These beds have been considered to be Great Oolite, but I am of opinion they are 

 true Inferior Oolite, as Mr. Reed obtained, at Whitwell, with Stomechinus germinans, 

 Gervillia Hartmanni, Miinst., the large quadrate Inferior Oolite variety of Trigonia costata, 

 Sow., and other well-known Inferior Oolite shells. It is by mistake that this urchin has 

 been said to be found in the Coralline Oolite at Malton, as I shall endeavour to show in 

 the history of the species. The Echinus diademata, M'Coy is a small Whitwell specimen 

 of St. germinans. From the facts before me, I conclude that this is a true Inferior Oolite 

 species, and the first and most typical of the genus to which it is referred. 



History. — This urchin was first figured by Professor John Phillips, in his ' Geology of 



