148 PEOP. P. M. Duncan's eetision op the 



Genus B-otuloibea, B. EtJieridge, 1 872, Quart. Journ. Geol. Soc. 

 vo]. xxviii. p. 98. 



Test moderate in size, tliick, very depressed, broadly ovoid, 

 longer than broad, actinally sligMly concave. 



Apical system small, central, circular ; madreporite large, 

 central ; tbe genital pores on its flanks. 



Ambulacra subpetaloid, widely open, with rather broad pori- 

 ferous zones ; inner pores circular, outer elongate ; and more or 

 less tumid interporiferous areas ; actinally five perforated furrows, 

 ramifying towards the margin. 



The interradia larger than the ambulacra. 



Anterior margin of the test smooth and slightly acute ; pos- 

 terior margin broader and with many (12) fimbriations continued 

 actinally as grooves. Neither lunules nor cuts. 



Peristome central, pentagonal, sunken, Periproct small, 

 between the peristome and the posterior margin. Tubercles 

 equal, densely placed in areolae. 



Fossil. Miocene : N. Africa. 



Pamily CLYPEASTEIDiE. 



Syn. Ecliinanthidce (subfamily), A. Agassiz, 1872-74, Eevision, 

 p. 510. 



Test small to very large, depressed, flat, to high ; margin sub- 

 pentagonal or subcircular, sharp to very tumid. Apical system 

 central, the basal plates fused together, all perforated by the 

 central madreporite ; genital pores beyond. Petaloid parts of the 

 ambulacra highly developed, usually unequal, the actinal furrows 

 straight. 



Interradia actinally discontinuous, one peristomial and two 

 apical plates in each. Jaws large, tall, wide above, the teeth 

 in vertical grooves on the inner part of the pyramids. Peri- 

 gnathic processes tall, narrow, two on each ambulacrum, fitting 

 in below the jaws. Internal structure various, always with 

 needles and pillars extending from floor to roof and expanding, 

 placed so as to limit the ambulacra incompletely from the in- 

 testinal areas, extending considerably towards the peristome ; 

 there may or not be a development of the pillars close to the 

 edge of the test, and a more or less complete fusion of them 

 into partitions arranged concentrically, so as to form inner walls ; 

 there may be an inner wall to the ambulacra protecting and 



