from the Island of Malta. 117 



tubercle; the poriferous zones lie in angular depressions of the 

 test, which, added to the convexity of the ambulacra, give a 

 much greater relief to the petaloidal star than in other congeneric 

 forms ; the rosette formed by the petaloid portions of the ambu- 

 lacra is small, being only a little more than one-half the diameter 

 of the antero-postcrior axis. The two rows of pores in the pori- 

 ferous zones diverge gently from each other from the apex to the 

 base, and there are from thirty to thirty- six pairs of holes in 

 each zone. At the junction of the test-plates there are slight 

 depressions on the surface, corresponding to the sutures between 

 the same ; the tubercles are small and set rather closely together, 

 and the intervening granulation is quite microscopic ; the border 

 is exceedingly thin and entire ; the base is concealed by firndy 

 adherent matrix, which cannot be removed without fracturing 

 the test. 



Affinities and differences. — C. folium is allied to the young 

 condition of C. marginatus, but the general flatness of the dorsal 

 surface, and the absence of the campanulate elevation of the 

 ambulacra in that species, added to the greater wideness of the 

 basal opening of the petaloid ambulacral areas, and the more 

 angular depression in the poriferous zones, afford points of 

 comparison whereby these two species may be distinguished 

 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 w-e 

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

 it w'as obtained from bed No. 3. 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. 



Histury. — This species is enumerated in the ' Cat. rais.' of 

 Agassiz and Dcsor, and stated to be " espece tres plate, a bords 

 tranchant.^' A detailed description of this interesting form is 

 now given for the flrst time. 



Genus Scutella (Lamarck, 1816). 



Form in general suborbicular, extremely depressed, almost 

 always discoidal, more or less eidarged 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 sj)ongy madreporiform body ; base flat ; mouth small. 



