i86 Cincinnati Socicly of Natural History. 



of the longest diameter, and with a pointed end, the concave 

 surface of the groove covered with fine transverse striae; 

 calices circular and polygonal ; stellate maculae distributed 

 irregularly over the surface, little or not at all elevated, and 

 sub-solid, or with a larger cell in the center; walls of cells 

 thin ; interstitial cells and spiniform corallites few ; seven 

 or eight calices to one-tenth inch between the maculae, but 

 fewer in number on the maculae ; corallites thin-walled, 

 with a direct course from the base to the upper surface ; 

 tabulae closely set with, in some cases, a series of vesicles 

 attached to one side of the tube, and extending half way 

 across, being met by horizontal tabuke from the other side ; 

 corallites circular, with a curved line from side to side, giving 

 a crescentric appearance. (Jour. Cin. Soc. Nat. Hist., vol. 7, 

 1884, p. 138.) 



Locality. — Danville and Frankfort, Ky. 



Remarks. — This species, characterized mainly upon the 

 presence of the conical groove on the under surface, is abun- 

 dant in beds of Trenton age at Frankfort, Ky., and in upper 

 beds of the Cincinnati Group at Danville, Ky. It is possible 

 that it may prove to be the form described by Nicholson as 

 selwynii var. hospitalis. This is stated to occur at Waynes- 

 ville, and to be parasitic upon shells of brachiopods. The 

 internal structure, especially the vesicles on one side and 

 straight tabuke on the opposite, is the same in both forms. 

 That described as falesi, however, seems to be made up of 

 tubes of one size only ; the other has both large and small 

 corallites. The conical groove is probably produced by the 

 growth of the coral upon a species of Hyolithrs, although 

 some have considered it to be the small end of an Orihoccras 

 or Endoceras. 



14. — M. PKT.vsiPORMis Nicholson. 18S1. 



Corallum free, conical or discoidal, varying in size from one- 

 half inch to nearly two inches in diameter, and also variable 

 in shape; under surface flat or concave, covered with a con- 

 centrically striated epitheca; corallites springing upward, at 

 right angles to the base, and giving rise to an exj^ansion thin 

 at the edges, and elevated in the center from one-half an inch 



