99 



Orthoceras medullars, Hall. 



Orthoceran medidlare, Tledl 1860. Rep. Progr. Geol. Surv. Wiscons. for 



1859, p. 4. 



" 1867. Twenthieth Rep. Reg. N. Y. St. Cab. Nat. 



Hist,, p. 353, pi. 20 (11), figs. 1 and 2. 

 Whiteaves.1884. This volume pt. 1, p. 37. 



Elora, David Boyle, 1876 : the specimen referred to on page 37 of the 

 first part of this volume. 



Orthoceras Scammoni, McChesney. 



Orthoceras columnare, Halll 1860. Rep. Progr. Geol. Surv. Wiscons. for 



1859, p. 4. But apparently not 0. columnare, 

 Marklin, 1857. 

 Scammoni, McChesney. .1861. New PalsBoz. Foss., p. 92. (Teste Hall.) 

 Boyii, " .. " 



lineolatum, " . . " " " " " 



irrcgulare, " . . " " " " " 



angvlatum, Hall 1867. Twentieth Rep. Reg. N. Y. St. Cab. 



Nat. Hist., p. 353, pi. 19 (10), figs. 10 and 11. 

 But possibly not 0. angvlatum, Wahlenberg, 

 1827. 



" columnare, Hail 1870. Rev. ed. Twentieth Rep. Reg. N. Y. St. 



Cab. Nat. Hist., p. 411, pi. 19, figs. 4, 6 and 8. 



" angvlatum. Hall 1870. Ibid., p. 413, pi. 19, figs. 10 and 11, and 



pi. 24, fig. 1. 



orus, Hall 1877. In first ed. of S. A. Miller's Am. Pal. 



Foss., p. 245. 

 Probably also Orthoceras Cadmus, Billings, 1866, Cat. Silur. Foss. Anticosti, p. 



83 ; ace. to Hall. 



The specimen of 0. CadmVfS from Elora referred to on page 38 of the 

 first part of the present volume, is a fragment of a longitudinally ribbed 

 and fluted Orthoceras, not quite an inch and a half in its maximum 

 length. Although identified with 0. Cadmus by E. Billings himself, it 

 is difficult to see how this fragment can be satisfactorily distinguished 

 from the 0. Darwini, Billings, of the Guelph formation, as that species 

 is now understood, or from the 0. bellatulum, Billings, from the Anticosti 

 group of Anticosti. 



A much more perfect specimen, which agrees perfectly with Hall's 

 figure.s of 0. angulatum, on Plate 1 9 of both editions of the Twentieth 

 Regent's Report, was collected by Mr. Thomas G. Connon at the Irvine 

 River, Elora, in 1887. This specimen, which has recently been pre- 

 sented to the Museum of the Survey by Mr. Connon, consists of a piece 

 of the septate portion of the shell about five inches in length, and a 



