ARCELLA. 27 



lar facets, bounded by prominent folds ; base rounded at 

 the border, inverted concavely infundibuliform ; mouth 

 circular, crenulated, mostly everted into the inverted 

 funnel. Sarcode-mass spheroidal, usually connected with 

 the mouth by a cylindrical neck. Pseudopods up to six 

 or more. Height, 80// to 180^ ; breadth at base, 72// to 

 168/<; at dome, 84,u to 200,u; mouth, 20^ to 80/u. Fre- 

 quent. 



Hob. Ponds. 



Arcettd dentata. SYN. : A. dentata, stellata, Ehr. ; A. stel- 

 laris, Okeni, Perty ; A. Plomceochlamis dentata, A. Heterocosmia stellata, 

 A. sticholepis stellaris, Ehr. 



Shell, as seen from above or below, circular and more 

 or less dentate, resembling a wheel with pointed cogs, in 

 side view crown-like ; breadth more than twice the 

 height ; dome convex and even, or depressed at the 

 summit, and broadly fluted at the sides ; base centrally 

 inverted, concavely infundibuliform, at the periphery 

 more or less everted, and divided into projections of 

 variable length. Mouth circular, entire. Sarcode like 

 A. vulgaris. Shell colorless or brown. Breadth, be- 

 tween the points of the base, 132// to 184//; height, 44/* 

 to 48// ; mouth, 40// to 44//. Not common. 



Hob. Same as A. vulgcvris. 



Arcetta artocrea. 



Shell from one-fourth to less than half as high as 

 broad; dome convex and even, or mammillated or pitted; 

 basal-border everted and rising from one-fourth to nearly 

 one-half of the height of the shell, obtusely angular and 

 entire ; central portion of the base inverted in the usual 



