FROM THE INFERIOR OOLITE. 315 



Description. — After a careful examination of all the evidence on the subject, I have come 

 to the conclusion that this is the urchin which was figured by Leske (tab. XLI, fig. 5), and 

 described by that author as Spatangites ovalis. The Anancliytes bicordata, Lamk. to 

 which it was formerly referred, is clearly the Spatangites bicordatus of Leske, and not the 

 S. ovalis of that author ; the confusion occasioned by this mistake, prevails throughout all 

 the works which treat of the species, down to that of our friend M. Desor, in 

 which its true synonyms, with one exception, according to our ideas on the subject, 

 are given in his excellent * Synopsis des Echinides Fossiles/ The Spatangus ovalis of 

 Parkinson and Phillips is a Coral Rag urchin, and in my opinion is the Spatangites 

 bicordatus of Leske. I reserve further details on this question until I give the 

 description of the latter species. 



M. Desor regards this urchin as an inflated variety of Disaster analis, Agassiz, and 

 preserves that author's specific name ; but surely, if we admit the identity of the 

 species, we should in justice to Leske retain his specific name ovalis. On comparing our 

 urchins, however, with the very excellent figure given of D. Analis by M. Agassiz, I 

 confess I have never met with so depressed a form as that figured in the ' Echinodermes 

 Fossiles de la Suisse ;' moreover, there is always an elevation before the apical disc, 

 amounting in some individuals to a monstrosity, which does not exist in I), analis ; the 

 posterior ambulacra, likewise, terminate at a greater distance before the anal opening than 

 in our specimens. 



The regular oval outline of this urchin forms a striking contrast to the orbicular and 

 sub-pentagonal figures of Collyrites ringens ; the sides are tumid; the dorsal and lateral 

 surfaces are smooth, and convex ; and the test has a uniformly gibbous appearance, with a 

 slight elevation on the upper surface ; the ambulacra are all complete, passing, without 

 interruption, from the mouth to their terminations on the dorsal surface, and on the same 

 level as the inter-ambulacra; the three anterior ambulacra converge near the junction 

 of the anterior with the middle third of the back, and the apex of the single area is 

 separated from those of the antero-laterals by the anterior pair of ovarial plates ; the 

 single ambulacrum is the narrowest, the postero-lateral are the widest ; and the antero- 

 lateral of intermediate width; the anterior border is sHghtly flattened, and lies in a 

 depression in the centre of this region ; the single area passes in a straight line from the 

 mouth to the vertex; the apex of this area rises into a small prominent triangular 

 eminence, which forms the highest point of the test, so that the vertex is situated at the 

 anterior thiixl of the back (fig. 1 c), whilst in Collyrites ringens, it is at the posterior third. 



The an tero -lateral ambulacra (fig. 1 c), curve gently upwards, backwards, and 

 forwards, from the mouth to the apical disc, thereby forming an undulated course. The 

 postero-lateral pair take a long sinuous course from the mouth, passing backwards, " 

 outwards, and upwards, over the posterior border, and terminate by making rather a sharp 

 curve at the upper end of the anal opening, or sometimes they form an arch immediately 

 over that aperture (fig. 1 d) ; the point at which these areas terminate, in this species, is 



