FEOM THE DISTRICT OF ATHABASCA. 119 



three-quarters in its maximum diameter. A piece of argillaceoiis limestone collected by Mr. 

 McConnell ou the Loou River is au aggregation of numerous small septate individuals of 

 this species, which average from about an inch to an inch and a quarter in their greatest 

 diameter. 



A single valve of a bivalved Aplychus, which may have belonged to this species, lies 

 closely appressed to one side of the outer volution and close to the aperture of the large 

 specimen from the Peace River, represented by figs. 3 and 3 a. This valve, which is thirty-one 

 millimetres in its maximum dorso- ventral diameter and twenty-nine in its greatest breadth, 

 is broadly subovate in outline, but subtruncate posteriorly. The median fold is narrow 

 but well defined and separated from the rest of the valve by a linear groove which diverges 

 slightly from the suture. The sculpture appears to consist of faint and almost obsolete 

 distant concentric plications, with a few obscure radiating stritp, nearly parallel with and 

 close to the furrow which bounds the median fold. 



This strongly ribbed Ammonite belongs to the group Angvlali of d'Orbiguy, and to 

 that section of the genus Hopliles which Zittel calls the group of Ammonites Deshayesii. 

 Its closest affinities appear to be with that species, especially in the suturai line, and to the 

 A. Feraudianus of d'Orbigny, ' but it differs from the . former in its much squarer outer 

 volution and straighter and bifurcating costse, and from the latter in its much narrower 

 umbilicus. 



ACANTHOCEBAS "WOOLGARI, Mautell. (Sp.) 



Ammonites Woolgari, Mantell. 1822. Greol. Sussex, p. 19Y, pi. xxi., figs. 16-22, and pi. xxii., 

 fig. 7. 

 Sowerby. 1828, Min. Conch., pi. 587, fig. 1. 

 Sharpe. 1853. Foss. Moll. Chalk, p. 27, pi. xi., figs. 1 and 2. 

 Ammonites percnrinat us, Hall & Meek. 1854. Mem. Am. Ac. Arts & Sci., Boston, vol. V., 



(n. s.), p. 396, pi. iv., fig. 2 (young). 

 Ammonites Woolgari, Meek & Hayden. 1861. Proc. Ac. Nat. Sc. Philad., p. 421. 

 Prionocyclus (Prionotropis) Woolgari, Meek. 1876. Rep. U. S. Geol. Surv. Terr., vol. IX., p. 



455, pi. vi., fig. 2, and pi. vii., figs. 1, a-h. 



Acanlhoceras Woolgari, Zittel. 1882-85. Handbuch der Palœontologie, vol. II, p. 477. 



A few characteristic specimens of this well known English species were collected by 

 Mr. McConnell, in 1880, ou the Athabasca River, at exposures ten miles above and three 

 and four miles below the mouth of the Pelican River, in the lower 200 feet of the La 

 Biche Shales, associated with Desmoceras Alhabascense. The largest of these specimens is a 

 nearly perfect cast of the interior of the shell, about fifteen inches and a half in its greatest 

 diameter, in which nearly the whole of the chamber of habitation is preserved, as well 

 as the septate portion. This specimen represents the adult state of the species as described 

 by Sharpe (op. cit., p. 27), in which the periphery is totally devoid of any keel or keels, 

 and the transverse ribs also are absent, the ornamentation consisting of two rows of very 

 prominent, large, conical and pointed tubercles, on each side of the outer volution, one 

 around the umbilical margin, and the other on the outer margin of the broadly flattened 



' " Paléont. Franc, Terr. Cret.," vol. I., p. 324, pi. Ixxvi., figs- 4 and 5. 



