280 THE CARBONIFEROUS SYSTEM. 



(c.) Gray or bluish earthy limestone, laminated and concretionary 

 (Kennetcook Limestone, Hartt) — Zaphrentis Limestone. Contains 

 Phillipsia Hoivi, Zaphrentis Minos, Cyathophyllum Steviacum, Spirifer 

 striata, Athyris subtilita {?), Productus semireticulatus, Strophomena 

 analoga, Edmondia Hartti, Cypricardia insecta, Orthoceras laterale, 

 Stenopora, and Fenestella. This limestone has been recognised by 

 Mr Hartt as the equivalent of the beds containing Zaphrentis and 

 Phillipsia on the Kennetcook River, and it can be identified with one 

 of the limestones of Lower Stewiacke. 



(d.) Brownish or buff-coloured impure limestone, very rich in shells 

 (Windsor Limestone, Hartt) — Aviculopecten Limestone. Tbis limestone 

 especially abounds in Lamellibranchiates, particularly species of 

 Aviculopecten, Pteronites, Macrodon, and Modiola. Naticopsis Howi 

 is also very characteristic. It also contains Productus cora (var.), 

 Terebratula sacculus, Rhynchonella Evangelini, Hartt, a Leperditia, and 

 a Serpula ; and the little coral Stenopora exilis is very common. Bake- 

 vellia antiqua also occurs in it, and a Conularia. The Brachiopods in 

 this bed are small and depauperated, indicating probably shallow and 

 turbid water. This limestone appears to correspond to the shell lime- 

 stone of Gay's River, near Wordsworth's, that of " Anthony's Nose," 

 Shubenacadie, and the yellow limestone of De Bert River. 



(e.) Compact gray shelly limestone (Stewiacke Limestone, Hartt), 

 Productus Limestone. This is the richest of all the beds in fossils, and 

 contains the greater number of those mentioned in the following lists. 

 More especially it abounds in Productus cora, Athyris subtilita, Tere- 

 bratula sacculus, Fenestella Lyelli, Macrodon Hardingi, Conularia 

 planicostata ; and it is the special habitat of Nautilus Avonensis, and 

 Orthoceras dolatum, 0. Vindobonense, 0. laqueatum, and 0. perstric- 

 tum. It is the equivalent of the upper or red De Bert limestone, 

 the Admiral's Rock on the Shubenacadie, and the Brookfield shell 

 limestone. 



Are these subdivisions of the Windsor limestones, as indicated 

 by Mr Hartt, merely local, or have they a more general value? 

 In writing to Mr Davidson, in 1862, I was inclined to believe that the 

 lithological differences in the Hmestones are local, and " may have 

 been caused through the limestones haviug been deposited in limited 

 basins or narrow straits, and probably at a time of much volcanic dis- 

 turbance," and that the only general distinctions are those between the 

 Lower limestones and the Upper, the former being " darker in colour, 

 more laminated, and less fossiliferous," and characterized by the preva- 

 lence of certain species of fossils. Mr Hartt's investigations have so 

 far modified these conclusions, that I am prepared to admit, for the area 



