Fossil Corals, — Loiver Silurian RocJcs o/* Canada. 125 



centre at the base, curving gracefully outwards. Each one of the tubes was 



tlie residence, or rather the hard external skeleton of a single Polyp, and 



when these were alive, no doubt the whole surface of the mass was covered 



with animal flowers, as in the Astra3a. The seas of the ancient Silurian epoch 



were perhaps quite as gorgeous as the coral reefs in the southern climes of 



the present day. 



Columnaria alveolata is confined to the Black River Limestone w^hicli 



lies just below the Trenton Limestone. Fine specimens may be collected in 



the quarry, where materials are now being procured for the Chatts Canal on 



the Ottawa. 



The Favosites Niagarensis mentioned in Article 6, pages 57 and 60, of 



this journal, and also Favosites Gothlandka, noticed in the quotation from 

 Sir Charles Lyell, at the commencement of the present article, very much 

 resemble this species externally. The difference is in the internal structure, 

 the walls of the tubes of Favosites being perforated by numerous small cir- 

 cular pores, and Columnaria unperforated. Alveolata appears to have been 

 derived from the Latin, {Alveare,) a bee-hive, or {Alveolus,) the holes in 

 which teeth are placed. 



Another genus of corals composed of tubes most prolific in the Lower 

 Silurian rocks of Canada, is ChMetes. Some of the strata in the Trenton 

 Limestone appear to be composed almost altogether of one species of it in 

 a fragmentary state. The tubes are exceedingly small, and they differ from 

 Astr(Ea and Columnaria in presenting no traces of radiating lamellaj. The 

 following is a description of the genus : — 



Genus Chcetetes, (Fischer.) 

 Generic Characters. — Corallum usually forming cylindrical branchesf 

 or hemispheric, or irregular masses composed of numerous long slender poly- 

 gonal tubes with transverse diaphragms, but no pores or radiating partitions. 



Fig. 11. 



Fig. 12. 



Fi?. 13. 



Figs. 11, 12, and IZ.—Diffcrent forma of 

 Chcetetes Lycoperdon. 



The above figures shew the most common forms of this coral. Fig. 13 



