from Sinai and Egypt. 221 



Dimensions 



L 3482. L 4323. M. oUsipponcnsis. M. cottenui.. 



Diameter 40mm. ... 33mm. ... 13-40mm. ... 2.5mm. 



Height 28 mm. ... 26 mm. ... ... 22 mm. 



Ratio of heiglit to cUam. 70:100 ... 78:100 ... 64 : 100 to ... 88:100 



88 : 100 



Distribution. — Egypt. Cenomanian : Jebel Gunneh (L 4323) ; 

 northern side of Jebel urn Eaiyig, north-eastern Sinai (L 3482). 

 Both collected by Dr. W. F. Hume. 



Figures. — PI. X, Fig. 4, a small specimen from the side, nat. size^ 

 from Jebel Gunneh, L 4323 ; Figs. 5a-f, plates from L 3482 from 

 Jebel um Eaiyig ; Fig. 5a, ambulacral plate from near the apical 

 area, by 4 diam. ; Fig. 5b, an ambulacral plate from the ambitus, by 

 4 diam. ; Fig. 5c, an ambulacral plate from the actinal surface, 

 by 4 diam. ; Fig. 5cl, an ambulacral plate from near the peristome ; 

 Figs. 5e and 5f, ambital interambulacral plates, by 4 diam. PI. XI, 

 Fig. 15, the ambital ambulacral and interambulacral plates of 

 M. cotteaui, Coq., after Cotteau. 



Affinities. — The nearest ally of this species is M. olisipponensis, 

 Lor.,' from the Cenomanian of Portugal, which differs by having 

 three regular granules on the ambulacral plates, and somewhat larger 

 granules on the interarabulacrals. It differs from the type-species, 

 M. cotieaid, Coquand,- by having an adoral demiplate, instead of 

 both the lower plates in the ambital ambulacral plates being 

 primaries. In this respect it resembles M. olisifponensis, which 

 agrees with M. cotteaui in the granulation of both the ambulaci'al 

 and interambulacral plates. 



Family CYPHOSOMATIDiE. 

 CYPHOSOMA, Agassiz. 

 Cyphosoma beadnelli, n.sp. (PI. X, Figs. 6, 7a-d, and 8.) 



Diagnosis. — Test of medium size, subcircular and low. 



Ambulacral plates composed of six constituents; each plate has on© 

 large tubercle, and a median row of coai'se scanty granules down the 

 middle line of each area. The scrobicular circles are confluent. 

 Interambulacra, 10 plates in a vertical series ; each bears one large 

 tubercle, round the base of which is an incomplete scrobicular circle, 

 a line of about 5 large granules on the inner and outer sides of the 

 scrobicular circle, which is incomplete above and below in the 

 ambital plates, so that the scrobicular areas are confluent. 



Dimensions : 



1 p. de Loriol: Cret. Fauna Portugal, vol. ii (1887), E'chitodermes, p. 62, pi. x, 

 figs. 3-6. 



2 Cotteau: Pal. fran^., Ten-, cret., vol. vii (1867), p. 823, pi. 1197. 



