2 28 THE GENUS MONTICULIPORA. 



a lono-itudinal series of lenticular vesicles on one side of the 

 tube. These vesicular tabulse terminate inwards by a con- 

 cave margin, and it is their cut edges which give rise to the 

 peculiar appearances presented in tangential sections. The 

 remainder of the corallite is occupied by a few straight tabulae, 

 which extend from the inner side of the lenticular vesicles 

 above mentioned to the opposite wall of the tube. The small 

 tubes, on the other hand, are crossed by numerous, close-set, 

 horizontal, and complete tabulce. 



The external and internal characters of this species are so 

 distinctive as to render a close comparison with other forms 

 unnecessary. I am much indebted to Mr John M. Nickles of 

 Cincinnati for kindly furnishing me with specimens. 



Horizon and Locality. — Cincinnati Group, Cincinnati, Ohio. 



Monticulipora (Peronopora) (?) Ortoni, Nich. 

 (PI. III. figs. 4-4^.) 



Chcetetes Ortoni, Nicholson, Quart. Journ. Geol. Soc, vol. xxx. p. 513, PI. 



XXIX. figs. 15-15^, 1874; Pal. Ohio, vol ii. p. 211, PL XXII. figs. 



3-3^, 1S75. 

 Atadopora Ortoni, Ulrich, Cat. Foss. Cincinnati Group, p. 13, 18S0. 



Spec. Char. — Corallum forming excessively thin sub-circular 

 crusts, which are attached parasitically by the whole of their 

 under surface to foreign bodies, and vary in thickness from 

 I -90th to I -50th inch, the breadth of the entire expansion being 

 usually under one inch. Surface exhibiting numerous minute 

 rounded or conical monticules placed at intervals apart of half 

 a line, less or more. Apertures of the calices about i-i25th 

 inch in length along their longest diameter, usually irregular 

 in shape, and often indented by one or more tooth-like and 

 blunt projections into the visceral chamber. Margins of the 

 calices very thick, studded with numerous blunt and rounded 

 tubercles, which give to the surface a peculiar granular aspect. 

 In the centre of the expansion the corallites are often nearly 



