i64 TABULATE CORALS. 



cono-eneric with C. Anticosticnsis, then it is clear that the genus 

 Cohimnopora has no relationships with Caiapcecia. This, at 

 any rate, seems to be the only conclusion that can safely be 

 arrived at, until the original specimens of Calapaxia shall have 

 been more fully examined and described. 



The geological range of Cohimnopora, so far as known, is a 

 very limited one, the type-species being confined to the Lower 

 Silurian (Cincinnati group) of North America. The type of 

 the genus is C. cribriforinis, Nich., of which I append the fol- 

 lowing brief description. Judging from the figures given, I 

 should imagine C. {Houghtonia) Huronica, Rom., to be at 

 most a variety of C. mbriformis ; but as the corallites are 

 apparently to a considerable extent disjunct, it may prove to 

 be a separate species when it shall have been examined by 

 means of thin sections. 



Columnopora cribriformis, Nicholson. 



(PI. VII., figs. 2-2 d.) 



Coliiinnopora crihriforinis, Nicholson, Geol. Mag., new ser., vol. i. p. 253, fig. i, 

 1S74; Pal. Ohio, vol. ii. p. 186, PL II., figs. 8-8/7, 1875; Second Rep. 

 Pal. Ont, p. 25, 1875. 



Spec. CJiar. ■ — Corallum forming hemispheric or pyriform 

 masses, which vary in diameter from ten lines to half a foot 

 or more, and in height from eight lines to three or more inches. 

 Corallites spreading from the base of attachment, essentially 

 polygonal, and for the most part in close contact, their walls 

 thick and fused together ; occasionally becoming subcircular, 

 and partially separated by narrow interspaces as their mouths 

 are approached. Calices rounded or distinctly polygonal, aver- 

 acjincr one line and a half in diameter, smaller ones beine often 

 intercalated here and there among those of ordinary dimen- 

 sions, their margins thick and crenulated by the septa. Septa 

 about twenty in number, more or less, in the form of strong 

 longitudinal ridges, which pass but a short distance inwards to- 



