82 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Dec. 8,
long, with from thirteen to sixteen ribs on each valve, of which from
three to four compose a moderately raised mesial fold. It measures,
length 7, width 8 lines. This is a Devonian shell, as it occurs
with Spirifera Verneuilii.
20. Rhynchonella Valpyana, n. sp. Pl. IV. figs. 26 & 27.
Shell small, pentagonal, longitudinally oval or ovate; valves moderately convex; surface ornamented with about thirteen simple ribs, of which the three largest in the dorsal valve form the mesial fold. Length 5, width 4, depth 3 lines.
Two or three internal casts and an external impression have been found by Messrs. Valpy and Vicary. It is, I believe, of Devonian age.
21. Rhynchonella Vicaryi, n. sp. Pl. V. figs. 7 & 8.
Shell small, somewhat trigonal and compressed, longer than wide, broadest anteriorly, tapering at the beaks; front straight; valves moderately and uniformly convex; surface smooth to about half its length from the beaks. Each valve is ornamented with eight or nine short ribs, of which three or four compose the fold, and two or four the sinus; beak small. Length 5-1/2, width 5 lines.
Of this small species I have seen several internal casts and external impressions. It was found by Mr. Vicary in the same pebble with Spirifera Verneuilii, and is consequently of Devonian age. It much resembles some Lower-Silurian specimens of R. Thomsoni, but could not be with certainty identified with that species.
22. Rhynchonella? ovalis, n. sp. Pl. IV. figs. 24 & 25.
Shell small, as wide as long, or rather longer than wide; ventral valve almost uniformly convex, with from eighteen to twenty simple ribs; dorsal valve regularly convex and ornamented like the other valve. Two specimens measured:—
Length 3, breadth 2-1/2 lines.
" 3 " 3
Of this small species I have seen a few internal casts and external impressions, but not sufficiently numerous or perfect to enable me to give a complete description of the shell. It has been found by Mr. Vicary in company with Orthis Vicaryi, and Strophomena budleignensis, and is possibly of Silurian age.
23. Orthis redux, Barrande?, var. budleighensis. Pl. V. figs. 9-12. Orthis redux, Barr.?, Salter, Quart. Journ. Geol. Soc. vol. xx. p. 295, pl. xvii. fig. 7, 1863; and Dav. Sil. Mon. p. 224, pl. xxviii. fig. 6, 1869.
Shell small, semicircular, wider than long, sometimes almost circular; hinge-line less than the width of the shell. Ventral valve moderately and uniformly convex, beak small, area narrow. Dorsal valve slightly convex, with a longitudinal depression of moderate depth along the middle. Surface of both valves closely covered with nume-
