112 BIOLOGICAL SOCIETY OF WASHINGTON. 



larly dotted with sporadic calyces, composed of circular gastro- 

 pores, each surrounded by a circle of five to nine dactylopores, with 

 occasional sac-shaped ampulla, which are most abundant on the 

 most elevated projections of the surface, and almost entirely absent 

 from depressed parts. Diameter of the dactyloporic circle about 

 i.o""™. ; of the central gastropore about 0.37™™. ; the distance from 

 center to center of the calyces varies from 1.5 to 2.5°"". 



Gastropores, cup-shaped, shallow (0.25-0.50"™.), smooth inside, 

 with the tip of a white spiculose nipple-shaped, or roundly conical 

 style in the bottom of each, projecting about its own diameter or 

 less into the cup through the aperture of a long nearly vertical 

 conical tube which it occupies and closely fills. The length of 

 this style, which resembles a fox's brush, is nearly equal to the 

 thickness of the coenosteum. The margin of the cup in fully de- 

 veloped gastropores is simple and entire, and depressed slightly 

 below (or in no case elevated above) the general surface. In im- 

 mature calyces there is frequently a shallow groove running from 

 the innermost point of each dactylopore toward or into the gastro- 

 pore. 



Dactylopores variable in number, eight seeming to be the normal, 

 but seven the most common number, never sporadic, in well-de- 

 veloped calyces entirely separated from the cavity of the gastropore 

 throughout their extent ; in immature ones joined to it by a shallow 

 superficial groove. Transverse section a little ovoid, the wider arch 

 away from the gastropore, and marked by a vertical, narrow, spongy 

 lamina forming the style.. The exterior margin simple, not elevated 

 above the general surface, but rather slightly depressed below it. 

 Neither sort of pore shows tabulre. Ampulla, simple sac-shaped 

 cavities as large as, or larger than, the calyces, not protruding above 

 the general surface, but more numerous on the prominences of the 

 crust. 



General surface between the above-described openings imper- 

 vious, nearly smooth, with the vermicular fine reticulations of the 

 coenosteum structure showing through the translucent substance, 

 and giving the surface a granular look, a vertical section of the crust 



