Prioniodus radicans Hinde, 1879

1879 Prioniodus radicans n. sp. - Hinde, pag. 356-357, Plate XV, fig. 1-6.

Original diagnosis - The central tooth relatively very long and robust, and gradually tapering to a point, either straight or with a more or less dextral or sinistral curvature. The lower portion is produced below the position of the lateral denticulate extensions, to form a single blunted termination or two or three small fang-like projections. The front portion is strongly convex in section, but nearly flat at the back, and a deep longitudinal groove extends at the back of the tooth from near the tip to the base. The lateral extensions, springing more or less obliquely from both sides of the main tooth, are narrow, straight, or slightly curved, strongly convex in front and with a groove like that of the main tooth at the back. They are frequently unequal in length and in the number of denticulations in the same specimen. These vary from 4 to 11, and are either short and blunt, or long, pointed, and slightly curved, in some cases of equal length on the same base, but frequently the central denticulations are the longest.

The teeth are smooth, black, and, where not much weathered, of a brilliant polish. The length of the central tooth varies from line to 18 line, the greater number are about 14 line. The lateral extensions vary between one third and two thirds the length of the main tooth. Though there is a great difference in form and size in these teeth, the extremes are connected by so many intermediate forms as plainly to indicate that all belong to a single species, and no other form but this appears to be present in these rocks.

This species is closely allied to P. volborthii, Pander (Monogr. p. 30, tab. i. fig. 1), from which it may readily be distinguished by the basal termination and the deep longitudinal groove of the main tooth, and the proportionately less development of the lateral extensions. I am unable to make any comparison of the relative dimensions of this and Pander's species, as unfortunately no reference is made by him either to the actual size of the specimen or to the scale to which the figure is drawn.

The species is abundant and well preserved, and occurs in beds of dark limestone, principally composed of the tests of Leperditia.

Occurrence - Grenville (Canada).

Age range - Upper (Hinde, 1879).

References:

- Hinde, G. J. (1879) - On conodonts from the Chazy and Cincinnati Group of the Cambro-Silurian, and from the Hamilton and Genesee-Shale divisions of the Devonian, in Canada and the United States. Geological Society of London, Quarterly Journal, vol. 35: 351-369p.