3'8 



ZOANTHAKIA. 



posed of polygonal corallites, which are usually directly connected by their 

 walls, and agree with those of the Favositidce in possessing a primordial 

 mural plate. A true ccenenchyma is in general wanting, but in some 



M 





ante 



^mR 



Fig. 201. — Michelinia convexa (D'Orbigny). Devonian. 



specimens the corallites are in places connected by the intervention of a 

 small quantity of exothecal tissue. The walls of the corallites are per- 

 forated by rows of large mural pores, which are placed close together and 

 give the wall a lattice-like appearance. The septa are in the form of 



Fig. 202. — a, A fragment of a colony of Syringolitcs Huronensis, Hinde, of the natural size ; 

 B, A single calice of the same, enlarged eight times, showing the central tube, and radiating lines 

 of septal tubercles ; c, Part of a corallite of the same, split open, and enlarged six times, showing 

 the composition of the central tube out of invaginated tabulae ; d, Part of a corallite of the same, 

 viewed from the exterior and enlarged six times, showing the mural pores. Niagara Limestone, 

 Alanitoulin Island, Ontario. (Original.) 



marginal ridges, and the tabular are complete and horizontal, and do not 

 give rise to a vesicular tissue by their union. 



described by the present writer under the head of Columnopora, and the latter 

 name must therefore be abandoned. Of the forms included by Billings under 

 Calaficecia, only one — viz., C. Anticostiensis — was figured,. and this proves to be 

 really quite different from the others, and to be nearly related to the genera Syrin- 

 vophyllum and Thecostegites. 



