from the Island of Malta. 119 



lacral sulci radiate outwards, which soon become bifid, each trunk 

 becoming dichotomously branched in old individuals. The anal 

 opening is round, about half the diameter of the mouth, and is 

 situate near the posterior border. The tubercles are small, and 

 closely placed together ; they are nearly of a uniform size on the 

 dorsal surface. 



Affinities and differences. — >S^. subrotunda so closely resembles 

 S. striatula, S. Faujasii, and S. producta, that it requires an at- 

 tentive study to discover the differences between them. As we 

 possess single specimens only of these forms, determined and 

 presented to us by M. Michelin of Paris, we are certain of their 

 identity with the types they represent. The test is narrower 

 before, and the ambulacral areas are much smaller in S. striatula 

 than in >S^. subrotunda -, the ambulacral areas are wider, their 

 bases and apices are more obtuse, their sides flatter, and their ter- 

 minations are more truncated, andthe anus further from the border 

 in S. product a than in 8. subrotunda ; the test is more convex on 

 the dorsal surface, the apical disc is wider, the margin is thicker, 

 the base flatter, and the anal aperture much further from the 

 border in S, Faujasii than in S. subrotunda ; the test is more 

 produced posteriorly, the margin is more sinuous, the ambulacral 

 areas are more equally lanceolate at the base and apex, the 

 inner row of pores of the same curve more gracefully outwards, 

 and the anus is further from the border in >Si. Brongniartii than 

 in S. subrotunda. The size and pyriform shape of the ambu- 

 lacral areas, the absence of sinuosities in the margin, and the 

 greater convexity of the dorsal surface, distinguish S. Paulensis 

 from S. subrotunda. 



Stratigraphical range and distribution. — This species is not un- 

 common in the calcareous sandstone bed No. 4, and in the junc- 

 tion beds of No. 5, the hard cherty limestone, at Malta. It is 

 found likewise '^ in the marine calcaire grossier in the environs of 

 Bordeaux ; at Bazas, Leognan, Gradignan, Douai, in Dauphine ; 

 in Tourraine; in Anjou; at Montpellier.'^ [Grateloup.) 



History. — The table of synonyms shows the phasis of the 

 history of this species, although other forms have been mistaken 

 for it : in fact, the species of Scutella approach each other so 

 closely, that, without an authentic series of specimens for com- 

 parison, similar mistakes may be made. This Urchin is found 

 in all the public collections. The specimens before us are from 

 Malta and Leognan. 



Scutella striatuhy Marcel de Serres. 



Syn. Scutella striatula, Marcel de Serres, Geognosie des Terrains 

 Tertiaires, p. 156 ; Desmoulins, Etudes des Echinides, no. 25. 



