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 Vernewili. 
20. RayncHonetta Vatpyana,n.sp. Pl. IV. figs. 26 & 27. 
Shell small, pentagonal, longitudinally oval or ovate; valves mode- 
rately 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, 1 believe, of Devonian 
age. 
21. RuyncHonrita 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 53, width 5 lines. 
Of this small species I have seen several internal casts and ex- 
ternal impressions. It was found by Mr. Vicary in the same pebble 
with Spirifera Vernewilii, and is consequently of Devonian age. It 
much resembles some Lower-Silurian specimens of R. Thomsonz, but 
could not be with certainty identified with that species. 
22. RHYNCHONELLA? OVALIS, n.sp. PI. 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 23 lines. 
29 3 39 3 99 
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 bud- 
leaghensis, 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. xvi. fig. 7, 1863; and Dav. Sil. Mon. p. 224, 
pl. xxvii. fig. 6, 1869. 
Shell small, semicircular, wider than long, sometimes almost circu- 
lar ; hinge-line less than the width of the shell. Ventral valve mode- 
rately 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- 
