GENERA OF FAVOSITID.E. 163 



plete. When the coralHtes are not in contact, the space be- 

 tween them is filled with a variously-formed vesicular tissue. 

 This genus resembles Heliolites, but differs therefrom in having 

 double the number of septa and the walls perforated." 



Two species were described by Mr Billings as belonging to 

 this genus — viz., C. Canadensis, from the Black River Lime- 

 stone, and C. Hiironensis, from the Hudson River formation. 

 The former is stated to have corallites about one line in dia- 

 meter, and generally in contact, although still remaining cir- 

 cular ; while the mural pores are arranged in horizontal rows 

 running all round the tube, one row between each pair of tabulse. 

 The latter was separated specifically from C. Canadensis, prin- 

 cipally upon the ground of the greater slenderness of its tubes. 

 Neither ot these forms was figured. From the above descrip- 

 tion it would appear that Calapceeia Canadensis and C. Huron- 

 ensis are corals nearly allied to the form which I have de- 

 scribed as Cobunnopora cribriforniis ; but such a conclusion has 

 been rendered very hazardous by the publication by Mr Bil- 

 lings, at a later date, of a third species of Calapacia, which was 

 both described and figured (Cat. Sil. Foss. of Anticosti, p. 32, 

 fig. 15, 1866). The species in question (viz., C. Anticostiensis^ 

 is stated to have a hemispheric corallum, the corallites some- 

 times in contact, but usually distant from one another by a 

 quarter or half a line. The shape of the corallites is circular, 

 and they are surrounded on the exterior by a fringe of well- 

 developed costce, while the spaces between them are subdivided 

 by horizontal and close-set exothecal plates. The septa have 

 the form of longitudinal striae, and tabula; were only obscurely 

 seen. In a note Mr Billings adds that this species would seem 

 to be congeneric with Syringophylluni orgammi. 



Whether or not Mr Billings be correct in the suggestion just 

 alluded to, the above description and the figures which accom- 

 pany it leave no doubt whatever as to the entire distinctness 

 of Calapoccia Anticostiensis, Bill, and Colunmopora crih-iformis, 

 Nich. If, therefore, the originally-described species — viz., Cala- 

 pceeia Canadensis and C. Hw-onensis — are to be regarded as 



