220 The Ottawa Naturalist. [December 



Several interesting varieties of Plectaynbonites sericea, Sow- 

 erby, also occur at this horizon and were collected. From a pre- 

 liminary examination of the forms obtained on this and previous 

 occasions, four distinct types may be said to occur. 



First, the small normal Trenton form, with its regularly 

 rounded anterior margin and very delicate, evenly and alternately ■ 



striated surface and non-ornamented shell. 



Second, a larger, conspicuously mucronate variety which 

 usually presents a rugose area immediately below the hinge-line on 

 the dorsal valve, the rugae are outwardly directed, and form a 

 conspicuous character in many individuals obtained. 



Third, a small globose or exceedingly tumid variety with 

 strongly arcuate valves and very minutely striated, with occasional 

 distant radiating lines from the beak to the anterior margin num- 

 bering from four to six in different individuals. (This variety bears 

 considerable resemblance to Leptcena qumquecostata , McCoy, from 

 the Ordovician of Ireland.) 



Fourth, the largest form usually classed under this designa- 

 tion, is one measuring nearly three centimetres in length and 

 more than one centimetre in height, with the anterior margin sub- 

 parallel for the greater part to the hinge margin, thus forming an 

 irregular parallelogram. This form is not infrequently met with 

 in the shales of the Lorraine formation in the vicinity of Quebec, 

 Montreal and Toronto, as well as of Ottawa. 



Besides the above notes on a few of the species obtained on 

 this cccasion further studies will no doubt reveal additional infor- 

 mation of a most interesting nature to the student of local 

 geology. 



The locality is not only prolific in fossils but readily accessible. 

 More than twenty species have already been recorded from this 

 horizon — the zone of Schizambon — and amongst these may be men- 

 tioned the Cirripede, described by Dr. Henry Woodward as 

 Turrilepas Canadensis, a number of opercular valves of which 

 were also obtained by the writer since the shipment of the original 

 specimens to Dr. Woodward from which the species was 

 described. 



The lower measures of the Utica formation, which consist at 

 this particular locality as well as at New Edinburgh and Roches- 



