MR J. W. GREGORY ON THE MALTESE FOSSIL ECHINOIDEA. 589 



Type.— Brit. Mus., E. 1868. 



Distribution. — Malta — Lower Limestone (Tongrian). Sicily — Calcare di Siracusa 

 (Helvetian ?). Egypt — Siuah Oasis (Base of Upper Miocene). 



Remarks. — This species is sharply marked off from the others by its very wide 

 miliary region, the numerous sharp but small granules of its scrobicular circles, and the 

 coalescence of these circles to a narrow band on the horizontal sutures. It is possible 

 that the specimen found by Baron Cafici is really one of C. scillce. 



Species 5. Cidaris oligocenus, n. sp. Plate L, fig. 2-4. 



Diagnosis. — Test probably circular ; depressed above ; turbinate. 



Ambulacra very sinuous and narrow ; one granule only on each plate, except on a 

 few at the ambitus, which bear a second but much smaller granule. 



Interradii: Of large, high plates, 5 or 6 in a vertical series. The scrobicular circles 

 are large, and the tubercles prominent. The scrobicular circles are never quite distinct ; 

 near the apical area they fuse to a broad band which separates the two scrobicular areas ; 

 but nearer the mouth these areas are confluent. Miliary region narrow. Tubercles per- 

 forate and non-crenulate. Spines large, sometimes cyathiform. 



Type.— Brit. Mus., E. 3401. 



Distribution. — Malta — upper part of Lower Coralline Limestone ; Ricasoli. Brit. 

 Mus. ; Geol. Soc. ; Leith Adams' Coll. 



Remarks. — This species belongs to the same group of species as does C. melitensis, 

 Wr., from the Upper Coralline Limestone. It clearly differs from this, in that the ambu- 

 lacra are more sinuous and much narrower. Dr Wright's figure {Ann. (2), xv., pi. iv. 

 f. 1, c) shows in his species a series of small granules on each ambulacral plate in 

 addition to the single tubercle of this new species. The narrowness of the miliary region 

 at once separates it from C. scillce and C adamsi. From C. avenionensis it may be 

 distinguished by the greater prominence of its scrobicular circles, which are distinct 

 except on the lowest. 



I entertain little doubt that this is the species figured by Scilla in the plates* which 

 Dr Wright quoted as illustrating his species C. scillce. Fortunately, however, Dr 

 Wright's type specimen is preserved in the Museum of the Geological Society, mounted 

 on one of his own tablets, and labelled by himself ; the fact that the miliary region was 

 apparently much narrower in the specimen figured by Scilla, Dr Wright probably 

 attributed to a misrepresentation in the drawing. Now, however, that some plates have 

 been found which agree with those figures, these may be taken as illustrating the new 

 species. Dr Wright's C. scillce may ultimately prove to be only a variety of C. adamsi. 



* De Corporibus Marinis Lapid., ed. 2, 1852, pi. xxiii. 1 f . 2 ; pL xxiii." f. 2 ; pi. xxiv. 



