1T2 W. A. Bell — Mississippian Formations of 



Northumberland, occurs in the upper Limestone of Wind- 

 sor. 



Correlation with the American Tennesseean. — The dis- 

 similarity of the Windsor faunas to those of like age in 

 the Mississippian basins of America was early noted by 

 Dawson and subsequently confirmed by Schuchert and 

 Beede. Dawson, moreover, clearly perceived their 

 European alliances and attributed their isolation from 

 the western faunas to the existence of an Appalachian 

 mountain barrier. The difficulties of correlating a fauna 

 which is dominantly a molluscan one are well exemplified 

 by the fact that Beede, who described faunas of this age 

 from the Magdalen islands, was impressed with the De- 

 vonian or early Mississippian aspect of some of the pel- 

 ecypods, whilst earlier paleontologists, e. g., Meek and 

 Newberry, emphasized their Permian appearance. In 

 the present correlation, reliance is placed rather on the 

 occurrence of several brachiopods and bryozoans that 

 either hold a limited range in, or make a definite entry 

 into, the Mississippi Valley basin. 



In the upper Windsor zone, several species belonging 

 to Martinia, Composita, and Productus present evidence 

 of an age synchronous with some part of the Chesterian 

 group. Martinia opertacosta n. sp. is a form closely 

 allied to M. contracta (Meek & Worthen). Composita 

 oUigata n. sp., common in, and characteristic of, the upper 

 Windsor limestones, is so close to C. subquadrata (Hall), 

 a characteristic Chesterian species, that it may well be 

 specifically identical. Productus (Avonia) multiplexi- 

 septum n. sp. is likewise probably specifically equivalent 

 to P. parvus (Meek & Worthen) from the Ste. Genevieve 

 and Chesterian groups. Thus there is direct evidence of 

 Chesterian affinities. Indirectly, the same conclusion is 

 reached, as the fauna of the upper zone at Windsor cor- 

 relates with that of a lower Dihunophyllum age in the 

 European time-scale. 



The lower fauna at Windsor, while it likewise indicates 

 Chesterian affinities, is seemingly an earlier expression 

 and may be in part equivalent to the Ste. Genevieve. The 

 Compositas, which are extraordinarily abundant in indi- 

 vidual representation, belong mainly to two species of 

 European stock, and while the productids of the cor a and 

 semireticulatus types are too plastic for correlation pur- 

 poses, they likewise are closer to the European species. 

 The occurrence in the fauna of a true JDiaphragmus is the 



