i8o Cincinnati Society of Natural History. 



large corallites. In the form described as Aspidopora parasitica 

 the species is occasionally parasitic, although even in this 

 when the object to which the specimen is attached is small, 

 the edges show a well-marked epitheca. We give below the 

 main features of the two species given as synonyms. In the 

 absence of illustrations reliance must be placed upon the 

 descriptions. 



Aspidopora parasitica Ulrich. Corallum adherent to foreign 

 bodies, but showing when over-growing the foreign sub- 

 stance a wrinkled basal epitheca ; corallites oval or circular, 

 moderately thin-walled, and arranged more or less circularly 

 about groups of cells larger than usual ; interstitial cells 

 numerous, but easily overlooked, on the surface; spiniform 

 tubuli numerous and recognizable in well-preserved speci- 

 mens ; cystoid diaphragms in the larger cells, but horizontal, 

 closely-set ones in the interstitial corallites; in tangential 

 sections corallites sub-circular or oval, in contact at two, 

 three or four points, interstitial cells occupying the interme- 

 diate spaces; spiniform tubuli at nearly all points of contact 

 between the corallites. 



Prasopora contigua Ulrich. Corallum hemispheric, base 

 flat or concave, one-half to three-quarters, rarely one inch in 

 diameter; cells polygonal and thin-walled, with groups of 

 cells slightly larger than the average at intervals ; interstitial 

 cells hardly discernable at the surface, but observable in 

 tangential sections, where they are wedged in between the 

 larger cells ; these last mostly in contact at their edges ; spini- 

 form tubuli also developed ; diaphragms cystoid, more fre- 

 quently excentric than central. 



It is scarcely necessary to make any further remarks as to 

 the relationship of these two "species" with M. ncwberryi. 



7. — M. ELEGANS Ulrich, 1880. 



Corallum free, thin, circular, from two lines to one and one- 

 half inches in diameter, and about one-fourth of a line thick ; 

 upper side convex, lower concave, but specimens generally 

 flattened by compression ; under surface smooth, or with an 

 epitheca having concentric or sometimes radiating striae; 

 upper surface with numerous, rather low, rounded tuberosi- 



