from the Island of Malta. 71 



from each other : the thinness of the border and flatness of the 

 dorsal surface are diagnostic characters by which it may be 

 known from its congeners. 



Locality and stratigraphical position. The only specimen we 

 know from Malta is that contained in Earl Ducie's collection ; 

 it was obtained from bed No. 2. We have another specimen 

 before us, kindly sent by M. Michelin from the Miocene terrain 

 of Balistro, in the Gulf of Santa Manza, Corsica. Agassiz and 

 Desor, on the authority of M. Deluc, give the tertiary of Palermo 

 as the locality of their specimen. 



History. This species is enumerated in the ' Cat. rais.' of 

 Agassiz and Desor, and staled to be " espece tres plate, k bords 

 tranchant." A detailed description of this interesting form is 

 now given for the first time. 



Genus SCUTELLA (Lamarck, 1816). 



Form in general suborbicular, extremely depressed, almost 

 always discoidal, more or less enlarged behind ; border often tren- 

 chant, disc entire, margin lobed; posterior border truncated; upper 

 surface slightly convex ; ambulacral flower small, with elegant, 

 flat, blunt leaves; poriferous zones forming nearly a closed 

 arch around them at their base ; genital pores four, set around 

 the spongy madreporiform body; base flat; mouth small, 

 central, and pentagonal, with five ramose ambulacral furrows, 

 sometimes branched, passing from the mouth to the border : 

 tubercles microscopically small and very numerous ; test thick, 

 interior divided by pillar-like processes : auricles five ; jaws 

 forming a more or less elevated star composed of five distinct 

 pieces, each formed by the organic union of two elements ; teeth 

 five, linear, and horizontal. This genus, as now limited, con- 

 tains only fossil species, one of which is from the chalk of 

 Georgia, United States; all the others are from the tertiary 

 rocks. 



Scutella subrotunda, Leske. 



SYN. Echinus Melitensis, Scilla, De Corp. Marin. tab. 8. figs, l-.'i. 



Echinodiscus subrotundus, Leske apud Klein, tab. 47. fig. 7. p. 206. 



Echinus subrotundus, Gmelin, Linne by Turton, vol. iv. p. 152. 



Scutella subrotunda, Lamarck, Animaux sans Vert. 2nd ed. torn. iii. 

 p. 284 ; Defrance, Diet. Sc. Nat. torn, xlviii. p. 230 ; Des- 

 moulins, Etudes des Echinides, no. 24. p. 232; Grateloup, 

 Ours. Foss. pi. 1. fig. 1. p. 36 ; Agassiz and Desor' s Cat. rais., 

 Ann. Sc. Nat. torn. vii. p. 132. 



Test very flat, suborbicular; dorsal surface slightly convt \ ; 

 ambulacral areas exceeding in length the semi-diameter of the 

 VOL. n. Q 



