452 ME. S. S. BUCKMAN ON THE BAJOCIAN [Aug. 1895, 



4 plaits, and none, so far, with 1 plait. The percentage of a series 

 is roughly thus : with 2 plaits 54*5, with 3 plaits 35*5, with 

 4 plaits 10-0. 



Rhynchonella cynica occurs chiefly in the Yeovil Sands around 

 Bradford Abbas, in the hard sand-burrs, so that its extraction un- 

 injured is rare ; it is also occasionally found in the ' Dew Bed ' at 

 Bradford Abbas ; it is rarely met with at Ham Hill in the stone- 

 beds, but as they are composed of broken shells it may have lived 

 there abundantly ; it also occurs in the Northampton Sands in the 

 neighbourhood of Northampton, 1 where it is known as Rh. cyno- 

 cephala, and specimens (differing from typical cynoprosopa in want 

 of elevation of the mesial fold, and not unlike cynica) occur in Moorei, 

 and, I think, aalensis-be&s of Coaley Peak and Penn Wood : they 

 have been confounded with Rh. cynocephala {cynoprosopa) and 

 consequently somewhat overlooked ; but they are to a certain extent 

 intermediate between cynoprosopa and cynica. 



The Dorset specimens of Rh, cynica lived at a later date than the 

 Gotteswold species, Rh. cynoprosopa, namely, in the Moorei hemera. 

 The Northampton specimens come from beds deposited at about the 

 same time {Moorei) or a little later — later at any rate than the beds 

 containing cynoprosopa ; and cynoprosopa is not known in Dorset. 



As the type of Rh. cynica I take the specimen with two plaits on 

 the mesial fold — this being rather the commoner form — represented 

 by Davidson, App. to Suppl. pi. xx. fig. 8. 



Bhynchonella cynomoepha, sp. n. (Pi. XIV. figs. 2-4.) 



1882. Rhynclionella cynocephala, var., Witchell, ' Geology of Stroud,' p. 47. 

 1887. Rhynchonella cynocephala, var., S. Buckman, ' Inf. Ool. betw. Andoversford, 

 etc.,' Proc. Cotteswold Nat. Field-Club, vol. ix. p. 115. 



A Rhynchonella like Stephensi or cynoprosopa, but always much 

 smaller, and differing in the greater number of plaits on the 

 lateral folds. The mesial fold has somewhat parallel sides, like 

 cynoprosopa, but more curved longitudinally in respect of the 

 ventral valve. 



This species is, in general characters, like Rh. Stephensi and 

 Rh. cynoprosopa, but it never attains to the size of either of them. 

 It is more like the latter, in that the mesial fold is well elevated, 

 the angle with a line from the beak to the lateral fold being about 

 70° ; also the mesial fold is of fairly uniform width. It differs 

 from Rh. cynoprosopa by its smaller size, by the greater number of 

 ribs on the lateral folds, by greater gibbosity of these folds in both 

 valves, and by somewhat greater curvature of the mesial fold of the 

 perforate valve. From Rh. cynocephala it differs by its more raised 

 mesial fold of more uniform width, from Rh. Stephensi by the same 

 character, by the greater number of ribs on the lateral folds, and 

 by all ribs beginning nearer to the beak and umbo. 



The species varies as to the number of plaits on the mesial fold, 

 but the 2-plait form is most frequently found. Out of a series 



1 Sent by Mr. B. Thompson, RG.S. 



