84 WHITEAVES ON THE OETHOCERATID.E OP 



an abnormally flattened specimen of this species, in which the outline of a transverse 

 section at the larger end (fig. 3a) is elliptical and not circular. 



ACTINOCERAS BlGSBYI, Bronu. 



Plate X, fig. 2. 



Orthocerœ . . . Bigsby. 1S24. Trans. Geol. Soc. Lond., ser. 2, vol. i, p. 198, pi. xxv, fig,s. 1 and 2 (but not 3). 

 Actinoceras Bigsby!, Bronn. 1S37. Lethœa Geogn , Bd. i, p. 98, Taf. i, f. S (after Bigsby). 



« " Stokes. 1840. Trans, Geol. Soc. Lond., ser. 2, vol. v, pt. 3, p. 707. 



Actinoceras Lyoni, Stokes. 1840. Ih., p. 707, pi. lix, fig. 1. 



" " Castelnau. 1843. Syst. Sil. de l'Amérique Septentrionale, p. 32, pi. xvii, figs. 1, a, b. 



Ormoceras ienuifilum, Hall. 1847. Pal. N. York, vol. i, p. 55, pis. xv, xvi, and xvii, figs. 1, a, b. 

 Ormocems Lyonii, Hector. 18(31. Quart. Journ. Geol. Soc. Lond., vol xvii, p. 439 (Salter's determination). 

 OTthoctras Bvjsbiji, Billings. 1863. Geol. Canada, p. 149, figs. 107 a, b, and appendix, p. 949. 

 Orthoccras {AHiiioceras) Bùjshyi, Barrande. 1874. Syst. Silur. de la Bobême, vol. i. Texte iii, p. 734, and pl.s ccxxxi, 



figs. 4 and 5 (copied from Dr. Bigsby) and ccccxxxvii, figs. 10-1(!. 

 Orlhoceras (Ormociras) lenuifliim, Barrande. 1874. 76., p. 754, p). ccxxxvii, figs. 5-7. 

 Actinoceras Bigsbyi, Foord. 1888. Cat. Ceph. Brit, Mne., p. 1G8. 



Lower Fort Garry, Dr. Hector, 185T. East Selkirk, A. McCharles, 1884 ; a siphuucle 

 sixteen inches long and quite perfect posteriorly. Swampy or Beren's Island, Lake Win- 

 nipeg, J. B. Tyrrell, 1889 ; three specimens, two with the apical extremity preserved, 

 with its large foramen, and all with a considerable portion of the test remaining, though 

 its surface is weathered. Black Island, near Swampy Island, one specimen, in a similar 

 state of preservation to those from Swampy Island ; and Big Sturgeon Island, a portion of 

 a siphuucle, Messrs. Bowling and Lambe, 1890. Mouth of the Fisher River, Lake Win- 

 nipeg, D. B. Dowling, 1891 ; a portion of a siphuucle. 



The type of this species is from Thessalon Island, Lake Huron, where it was collected 

 by Dr. Bigsby in 1820. In the "Geology of Canada " (1863) A. Bigsbijiia recorded as 

 occurring, in Ontario, on Campement d'Ours Island, on the Palladeau, Manitoulin and 

 Lacloche Islands and on Snake Island, in Lake Huron,— at Loughborough, Dickson's 

 Mills near Pakenham, and Cornwall ; in Quebec, at Pointe Claire (on the island of Mont- 

 real), Montreal, St. Ambroise and Lake St John. The specimens from Montreal are from 

 the Trenton limestone, but all the others from the localities just cited, in the provinces of 

 Ontario and Quebec, are from the Black Eiver limestone. 



The " longitudinal, undulated, thread-like lines " which are said to be characteristic 

 of the outer surface of the shell of A. Bigsbyi are very rarely preserved. No traces of these 

 surface markings can be detected in any of the specimens from Manitoba, and scarcely 

 any in those from Ontario or Quebec. The species, however, can always be recognized 

 by its very peculiar siphuucle, which is usually well preserved. The lougitudinal sec- 

 tion of a specimen from Black Island represented on Plate X, fig. 3, shows the opening of 

 the large foramen directly into the endosiphou posteriorly, and some of the lateral canals 

 or tubiili which radiate first outward and then outward and forward, from the endosiphou. 

 Not a vestige of the chamber of habitation of this specie?, nor of that of A. Richardsoui, 

 have yet been discovered. 



