140 THE CANADIAN NATURALIST. [Yol. Vli. 



an outer area in which there is a set of imperfect diaphragms 

 projecting upwards, and bearing on their upper surfaces rudi- 

 mentary radiating septa. A thin complete epitheca, and a sep- 

 tal fosette." (Billiogs, Canadian Journ., New Series, Vol. lY., 

 p. 129.) 



The central space of the theca is occupied in corals of this 

 genus, as in Amplexus, by flat or slightly flexuous tabulae, upon 

 which the septa encroach slightly or not at all. Outside this 

 central area is a narrow zone in which the tabulae are bent down- 

 wards towards the base of the corallum, and are at the same 

 time occasionally split or bifurcated ; whilst the continuity of 

 the spac:s between them is interfered with by a series of strong 

 septa. Outside this, again, is an outer zone formed by a series 

 of tabulae which are directed upwards and outwards in an arch- 

 ing manner, and which carry on tlieir upper surfaces a series of 

 imperfect septa, their lower surfaces being simply costate or 

 ridged. Lastly, the tabulae of this external zone are walled in 

 by a thin but strong epitheca, with which the outer surface of 

 the coral is invested. 



The genus differs from ZapJu^enfis in not having the septa 

 prolonged inwards to, or near to, the centre, and in having the 

 central tabulate area surrounded by an intermediate imperfectly 

 vesicular zone, surrounded in turn by an exterior zone of arched 

 tabulae and incomplete septa. From Amplexus it is distinguished 

 by the possession of the exterior zone last mentioned, and by the 

 septa being more largely developed ; whilst it is distinguished 

 from CUsioj)hi/Uum by the first of the above-mentioned peculi- 

 arities, and also by the fact that the tabulae of the central area 

 are nearly or quite flat, and are not elevated into a conical pro- 

 tuberance. 



The genus BlothrophyUum was originally defined by Mr. 

 Billings (op. cif.), and the single species B. decorticatum was 

 described. In addition to this previously recorded and very 

 characteristic species, I have now to describe an allied form, B. 

 approximatum, also from the Corniferous limestone of Western 

 Ontario. 



II. Blotiirophyllum approximatum, n. sp.- 



Corallum of unknown length, cylindrical or cylindro-conical. 

 The outer area consisting of strong arched diaphragms, curving 

 upwards and outwards, distant from one another from half a 



