214 PEOF. P. M. DUisrcAisr s eevision op the 



Fossil. Tertiary (late) : Barbadoes. 



'Recent. Philippines; Tristan da Cunlia to Buenos Ayres ; Juan 

 Fernandez to CMli; Antarctic Ocean, Marion Island to Kerguelen 

 and Australia. Depth 1050 to 2225 fathoms. 



Grenus Caltmne, Wyv. Thomson, 1877, Voy. of the '■Challenger^ 

 '■'■The Atlantic^^ vol. i. p. 397. A. Agassiz, 1881, Beport on 

 ^Challenger ' Echini, p. 154. Loven, 1883, Pourtalesia, p. 90. 

 (Arranged.) 



Test moderate, and probably large in size, and very thin, oval 

 elliptical in marginal outline, longer than broad, and broader than 

 high, rather flat actinally, with a low rounded keel extending from 

 the peristome backwards, tumid above the slightly sharply-edged 

 margin, rather flat abactinally. Plates numerous, large, very 

 geometrical in shape. 



Apical system with the bivium widely separated from the trivium 

 by plates of the postero-lateral interradia ; anterior basals per- 

 forated by the genital ducts which protrude ; the madreporite is 

 placed immediately behind the basals 2 and 3, and is probably in 

 an intercalated plate. Behind the madreporite are two large 

 plates, one on either side of the median line ; and they appear to 

 be imperforate basals ; and behind these basals are four or five 

 plates of the postero-lateral interradia. The anterior radial 

 plate is in the usual place and is small; the antero-lateral 

 radials are on the outer edge of the large basals behind the 

 madreporite ; and the posterior radials are close and behind the 

 last of the intercalated interradial plates. The system is there- 

 fore elongate and disunited. Basal 5 is absent. 



Ambulacra flush, apetelous, uniporous ; plates large and high, 

 diff'ering but slightly in height from the interradial plates, the 

 pore being far in the middle of the plates. The anterior am- 

 bulacrum resembling the others and, like them, flush with the 

 test; the antero-lateral far forwards and on a line with the 

 peristome ; the postero-lateral far back abactinally, and with 

 broad parts on either side of the sternum. 



Interradia with the anterior pair much smaller than the pos- 

 tero-lateral, which are broad and which separate the bivium 

 from the rest of the calyx abactinally ; the antero- and postero- 

 lateral interradia reach the peristome, with very narrow single 

 plates. Posterior interradium narrower than the postero-lateral, 

 actinally forming the low keel of the sternum, its first plate 



