from the Island of Malta. 123 



apical disc small and nearly central; base convex; mouth 

 and anus large. 



Dimensions. — Antero-posterior diameter 2^^ inches, trans- 

 verse diameter 1 j^^j inch, height j^^^^^ ^^ ^^ inch. 



Description. — The form, size and structure of the ambulacral 

 areas afford the best guide to a knowledge of the numerous species 

 of this group. The Urchin before us has an oblong form, de- 

 pressed at the dorsal surface, convex at the base, and slightly 

 produced posteriorly. The ambulacral areas are narrow at their 

 widest part ; they are about one-sixth the width of the postero- 

 lateral interambulacra at the border. The poriferous zones are 

 narrow, and extend rather more than half-way down the dorsal 

 surface ; the pairs of pores are placed closely together, and the slit 

 or sulcus, which in general unites the inner and outer series 

 of pores together, is absent in this species, or at all events is not 

 apparent in the individuals before us ; the holes of both rows are 

 nearly of the same size. The interambulacral areas are wide; 

 the antero -lateral are the narrowest ; the single interambulacrum 

 is slightly produced in the region of the anal opening. The 

 apical disc is small, and situated near the centre of the test, 

 rather nearer the anterior than the posterior border. The disc 

 consists of a central madreporiform spongy body, around which 

 the genital and ocular plates are arranged in a circle ; their 

 sutural lines of union, however, are concealed, and can only be 

 seen in weathered specimens. The base is convex ; the mouth 

 is very large, and lies in a deep depression opposite the vertex ; 

 it is surrounded with five oral lobes of small size, with inter- 

 vening petaloidal depressions, perforated with holes in pairs. 

 The interambulacrum is slightly produced posteriorly. The 

 anus is a large transversely oblong opening, situated near the 

 margin. The border of the test is rather obtuse. The tubercles 

 are of uniform size on the dorsum, and are larger and less 

 numerous than in E. Kleinii, 



Affinities and differences. — This species resembles much E. 

 scutiformis, but is distinguished from it by the greater narrowness 

 of the ambulacral areas, and the absence of the transverse slits 

 or sulci by which the pairs of pores in these avenues are in 

 general united. The tubercles are more abundant on the dorsal 

 surface in E. Deshayesii, and the dorsal surface is not so much 

 elevated in that species as it is in E. scutiformis. 



Locality and stratigraphical range. — This species was col- 

 lected from bed No. 2, the yellow sand, at Malta. Desor gives 

 the " Tert. moyen. d'Oran (Algerie) et de Carthagene (Cata- 

 logue) " as his localities ; and we have received from M. Michelin 

 of Paris a specimen from the Miocene terrain of Balistro, Cor- 



