37 



of the siphuncle. The volutions of the shell in thai species are said to 

 be " very gradually increasing in size throughout and probably circular 

 in a transverse section when not compressed, but in the specimen used 

 and figured are of very much greater diameter in a dorso-ventral direc- 

 tion than laterally, giving a rather acute dorsal keel ; most likely due 

 to compression, the specimen being imbedded in the rock parallel to 

 the stratification." 



The outline of a natural transverse section of a specimen from Hes- 

 peler, which in other respects agrees well with the description of L, 

 multicostatvs, is transversely sub-elliptical or subreniform, its dorso- 

 ventral diameter is much less that its breadth laterally, its periphery is 

 broadly rounded and somewhat flattened, and there is not the slightest 

 indication of a keel. The siphuncle is small and situated in the centre 

 of the inner margin of the whorls, and the species appears to be a true 

 TrocJwUtes, very closely allied to the T. ammonius of Conrad. 



Orthooeras crebescens, Hall. 



Orthoceras crebescens, Hall 20th Eeg. Eep. St. of N. Y., p. 354, 



pi. 19, figs. 1, 2, and 3. 

 Orthoceras crebescens, Hall and Whitfield. Pal. Ohio. Vol. 2, p. 148, pi. 9, fig. 2. 



Hespeler, T. C. "Weston, 1811 : Elora, Mr. James Gladstone, 1876, and 

 since presented by the Trustees of the Elora Public School Museum per 

 Mr. David Boyle : Durham, Mr. J. Townsend. 



The Hespeler specimen is a coarse cast of the greater part of the 

 body chamber, measuring eight inches and a half in length by four and 

 a quarter in breadth at the larger and three and a half at the smaller 

 end. The fine example from Elora is entirely septate and is divided 

 into fifteen chambers ; it measures rather more than eight inches and 

 a half in length by three and a quarter in breadth at the larger and two 

 and a third at the smaller end. 



Orthoceras medtjllare. Hall. 



Orthoceras medidlare, Hall. Eep. Progr. Geol- Surv. of Wisconsin, 1859. 

 " " TwentiethEeg. Eep.,p. 353, pi. 20. 



Elora, collected by Mr. David Boyle in 1876, and since presented by 

 the Trustees of the School Museum. 



A large cast of the septate end of the shell, measuring about seven 

 and a half inches in length, with a portion of the test preserved. The 

 septa are distant about one-third the lateral diameter, and the siph- 

 uncle is partly exposed on one side of the small end. 



