LYMN^EIDJE OF NORTH AMERICA. 



439 



one to eight are very uniform in oronensis; the ninth lateral has a 

 small indication of an entocone, the tenth and eleventh teeth are typi- 

 cal intermediates with well-developed entocone and ectocone; the 

 twelfth tooth has usually a bifid entocone, while the thirteenth tooth 

 is a normal intermediate. The fourteenth tooth and all which fol- 

 lows are typical marginals, with irregularly serrated margin ; the meso- 

 cone persists in a few marginals, but all of the cusps become sub- 

 equal at about the seventeenth tooth. 



Genitalia : Not examined. 



Range: (Figure 49). Maine to eastern Ontario. A species of 

 the Canadian and Nova Scotian regions and of the Boreal (Canadian), 



i to ns 



loo ti 



Fig. 49. 



Transition and Upper Austral life zones ; it is confined to .the Atlantic 

 drainage. 



RECORDS. 

 United States. 

 Maine: Lincoln, Penobscot River, Penobscot Co. (Bost. Soc. N. H.) ; 

 Orono, Penobscot Co. (Bolles; Stearns; Walker); Lake Auburn, Androscoggin 

 Co. (Lerrnond) ; Caribou River, Aroostook Co. (Nylander). 



British America. 

 Ontario: Ottawa, Carleton Dist. (Latchford; Heron; Walker). 

 Geological Distribution : Unknown. 

 Ecology : Not differentiated from emarginata. 



