THE BBACHiOPODA. Sf 



only in the Murcliisonae zone, and is rather scarce. It is a very 

 constant species. 



Dimensmis. — Length, 7 ; breadth, 12 ; depth, 9. 



Localities. — Bradford Abbas and Marston Eoad (Dorset), also 

 near Cheltenham (Gloucestershire). 



36. — Ehynchonella eingens, Herault. 



1851. Ehynchonella ringens, Davidson, British Brach. Palseont. 

 Soc, plate xiv., figs. 13-16. 



1877. ,, EINGENS, Dav., Proc. Dorset Club. Vol. I., 



plate iv., figs. 17 and 18. 



This well marked species is most peculiar in its geographical 

 distribution, being at some places very common, and at others, 

 where its bed also occurs, it is extremely rare. Thus, at Half- 

 way House, and near Sherborne, in Dorset, and near Corton, 

 Somerset, it is common, but at Bradford Abbas it is extremely 

 rare, and at many other places where the bed occurs it is not 

 found at all. The young of this species are very peculiar, the 

 smaller they are the flatter they become, until the median fold is 

 hardly perceptible. Again, when they are about half grown 

 they are extremely hard to distinguish from the variety of 

 Rhynch. cynocephala with one plait. Rhjnch. ringens generally 

 has only one large median fold, but occasionally this is slit at 

 the top into two (as shown Dav. Proc. Dorset Club, Vol. I., 

 pi. iv., fig. 18), and into three (as shown in a French specimen 

 Dav. Palceont. Soc, 1851, j)late xiv., fig. 16). Specimens of 

 both of these variations have occurred in this neighbourhood 

 Since the publication of Mr. Davidson's paper in the " Proceed- 

 ings of the Dorset Field Club," much larger s^jecimens of 

 Rlujncli. ringens have been obtained. 



Dimensions. — Length, 6 ; breadth, 8 ; dejith, 8 lines. 



Localities. — Halfway House, near Sherborne, &c. (Dorset) 

 near Corton (Somerset). Oppel quotes it from Moutiers (Calva- 

 dos). 



