Prof. H. A. Nicholson — New Devonian Fossils. 13 



are Brachiopods, and the remainder are distributed amongst the 

 Polyzoa, Gasteropoda, Lamellibranchiata, Annelida, Trilobita, and 

 Crinoidea. 



Genus Callopora, Hall. 



Gen char. — Corallum compound, massive, encrusting- or ramose ; 

 corallites minute, tubular, separated by a still more minutely tubular 

 ccenenchyma. The coenenchyma always rendered vesicular by 

 numerous transverse diaphragms, and the corallites also generally 

 tabulate. Septa rudimentary or absent. 



The genus Callopora includes a number of corals which range 

 from the Upper Silurian (Niagara group) to the Devonian, and 

 which in some instances have decidedly the aspect of Polyzoa. The 

 affinities of the genus are, however, beyond question, so far at any 

 rate as concerns those species which have come under my observa- 

 tion. Callopora, beyond all doubt, is a genus of Tabulate Corals, 

 and finds its nearest allies in the genera Heliolites and FistuUpora. 

 From the former of these Callopora is separated by the absence of 

 septa, and from the latter by the fact that the tubuli of the coenen- 

 chyma are regularly tabulate, whilst the corallites themselves 

 have the theca either open or partitioned off by a few remote hori- 

 zontal tabulse. There is also a much greater disproportion between 

 the size of the corallites and that of the tubuli of the coenenchyma 

 than is the case with FistuUpora. 



One large species of Callopora, which perhaps may subsequently 

 be found to admit of subdivision into two, has occurred to me in 

 the Devonian formation of Western Ontario; and this is clearly 

 distinct from all previously recorded forms. 



Callopoka incbassata, Nicholson. Plate II. Fig. 1. 



Spec, cliar. — Corallum sometimes encrusting foreign bodies, some- 

 times forming large expansions, or sometimes constituting hemi- 

 spheric or globular masses, which are composed of numerous con- 

 centric layers superimposed one upon the other. Corallites very 

 minute, tubular; their circular calicos slightly elevated above the 

 general surface, and surrounded by a prominent margin. From 

 three to five calicos in the space of one line, separated by intervals 

 of from half to two-thirds of their own width. Corallites some- 

 times with the cavity of the theca undivided, but more commonly 

 partitioned off by a few remotely placed horizontal tabulae. Coenen- 

 chyma composed of exceedingly minute tubuli, which are divided 

 by close-set horizontal diaphragms. The surface exhibits, at 

 intervals of about two lines, elongated star-shaped spaces, sometimes 

 smooth, sometimes punctate or minutely pitted, which are not pene- 

 trated by tubes of any kind, and appear to be quite solid. There 

 are generally from three to six corallites surrounding these vacant 

 spaces which are larger than the average, and the spaces themselves 

 have a long diameter of from one to two lines by a shorter diameter 

 of half a line. In some specimens, also, the surface exhibits oc- 

 casional large conical elevations, pierced each by a single canal, the 

 diameter of which is about one line, and which descends vertically 

 into the mass. 



