1869.] DAVIDSON—PEBBLE-BED BRACHIOPODA. 79
scribe it as such. But we have a British species of Orthis (O. spiriferoides),
in the Caradoc Sandstone, which exactly resembles it in
outline and convexity. Otherwise I might believe, with my friend
M. de Verneuil, that it was a Devonian fossil introduced into these
beds. It would seem that there is at least one allied species of
Spirifer in the French Silurian deposits, S. Davidis, Rouault." The
Budleigh species, however, is quite distinct from Orthis? spiriferoides.
11. Spirifera macroptera, Goldf.?, var. microptera. Pl. IV. figs. 21 & 22.
Shell semicircular, much wider than long, valves convex, hinge-line as long as the width of the shell, cardinal angles acute, with mucronate wings; fold smooth, with a slight depression or flatness in the middle; lateral portion of valve ornamented with about twelve ribs, or twenty-four on each valve. Length 6, breadth 15 lines.
This shell is not abundant; it has been found once or twice in the same pebble with S. Verneuilii and Rhynchonella inaurita. I am not, however, quite certain with reference to the correctness of my identification of it with Goldfuss's S. macroptera; but I know of no nearer form with which it can be at present compared.
12. Spirifera octoplicata, Sow.? Pl. IV. fig. 23.
In external shape the Budleigh specimens closely resemble the Devonian and Carboniferous species; but some examples are also not unlike S. elevata of Dalman. It occurs sparingly in the same rock with a Strophomena, Orthis Vicaryi, and two or three other forms. It differs also in the respective number of lateral ribs.
I could make out with certainty no more than the three species above recorded; but one or two imperfect internal casts have been found which may perhaps belong to another Spirifera.
13. Nucleospira Vicaryi, n. sp. P1. IV. figs. 15-18.
Shell transversely suborbicular; valves moderately convex, most so near the beaks. In the dorsal valve the mesial fold is wide and of small elevation, rising towards the front; beak of ventral valve small and incurved; surface smooth, marked by a few lines of growth. In the interior of the dorsal valve the bifid cardinal process projects considerably, while under it rises a narrow ridge which extends to the front and thus divides the shell into two portions. The muscular impressions lie on either side of the posterior half of this ridge. In the interior of the ventral valve a mesial ridge is likewise present, which, as in the dorsal one, divides the shell into two equal parts. On either side are located the muscular impressions. Two examples measured respectively:—
Length 7, breadth 9, depth 2 lines.
" 5 " 6 lines.
This remarkable species seems referable to the genus Nucleospira, and approaches, by its size and character, to N. elegans, Hall (Pal. N. York, vol. iii. p. 222, pl. xxviii. B, figs. 10 & 15). It varies in
