86 PROCEEDINGS COTTESWOLD CLUB 1905 
like the normal. form of Zer. wethingtonensis (fig. 8 
Buckm.) the chief distinction being that the line of junc- 
tion of the valves, when viewed laterally, describes a 
continuous curve from the beak of the frontal margin, 
whereas in 7er. wethingtonensis it is a sigmoidal curve, 
often markedly so. 
So long a period elapsed between the time of the exist- 
ence of Mr Buckman’s species and that under notice that 
I do not feel justified in referring it to his species ; more- 
over, I do not look upon the shell as belonging to a type 
which had during that lapse of time maintained its form 
without material modification, but as a degenerate form— 
its degeneration being probably due to unfavourable en- 
vironment. I do not know what the immediate ancestor 
was, but I suggest that it is not unlikely to have been 
Ter. notgroviensis, S. Buckm. I propose to call it Zer. 
degenerata. 
3. TEREBRATULA DEGENERATA, sp. nov. 
Pl. III., figs. 11—13. 
DIAGNOSIS.—Shell small, almost circular, slightly longer than 
wide, uniplicate, the fold rising gradually from the extreme 
lateral margins of the valves, valves about equally convex, 
moderately inflated, beak very short; foramen large, 
extending almost to the umbo, deltidial plates very small. 
I have found the shell in the Lower 7¢gona-Grit at the 
Frith, near Stroud, where the form appears to be constant. 
A more elongate, but in other respects similar shell occurs 
sparingly in the same beds at Ravensgate Hill and Leck- 
hampton Hill.’ 
There are a number of well recognised uniplicate Tere- 
bratule in the Inferior Oolite, eg. I. Etheridget, Dav., 
TZ. withingtonensis S. Buckm., 7. Buckmani Dav., and 
1 “ Handbook Geol. Cheltenham ” (1904), PP, 77, 104. 
