362 P. E. Raymond — Fauna of the Chazy Limestone. 



Sandstone. Limestone. 



Lingula lyelli. Lingula lyelli. 



* Camarotoechia plena. * Cam arotoec/iia plena. 



* C. or 'ten talis. *Rafinesqnina alter nata. 

 Hebertella imperator. 



Modiolopsis breviuscula. Modiolopsis breviuscida. 



31'. parviuscula. M. parviuscula. 



M. soioteri sp. nov. 

 Ctenodonta parvidens sp. nov. 

 Whitella canadensis sp. nov. 



* Archinacella f deformata. 

 *Raph istom a striatun i . 



*R. stamineum. Haphistoma stamineum. 



Lophospira billingsi sp. nov. Orthoceras allumettensis. 

 Bathyurus angelini. Bathyurus angelini. 



JBeyrichia elavigera. Leper ditia amygdalina. 



B. elavigera clavifracta. *L. canadensis. 



Leperditella labellosa. 

 JPrimitia sp. Lsochilina ottaioa. 



Isochilina sp. L. amiana. 



Primitia logani. 



It may be seen from the above parallel lists that there are 

 only 6 species common to the sandstone and limestone divisions 

 of this formation. In the limestones the ostracods are exceed- 

 ingly abundant, often making up entire layers of the rock. 

 The two divisions are intimately connected by very well- 

 defined species, however, and none of the forms pass on into 

 the overlying Lowville limestone. 



In the Ottawa Valley, the most noticeable feature of the 

 faunas is the absence of the cystids, Eryozoa, and Hydrozoa so 

 common in the typical Chazy. The large number of species 

 of ostracods and their great abundance are in marked contrast 

 to the three or four species found in the Champlain Yalley. 

 This difference in the lithology and fauna has led the writer 

 to suggest the name Aylmer* formation for these deposits in 

 the Ottawa Yalley. 



Summary on the Lake Champlain, Mingan Islands and 

 Ottawa Yalley Regions. 



In the Lake Champlain region occurs the fullest develop- 

 ment of both the strata and the fauna of the Chazy period, and 

 three divisions based upon faunal differences may be recog- 

 nized. The fauna of the Chazy at Mingan Islands, while only 

 partly known, shows that the typical Chazy is also found in 

 that region. West of Hawkesbury, Canada, a decided change 



* Ann. Carnegie Mus., vol. iii, p. 380, 1905. 



