THE BRACHIOfODA. 41 



Dimensions. — Length, 12; breadth, 14; depth 8 lines. Another 

 specimen: — length, 11; breadth, 13; depth 17 lines. On this 

 last specimen I counted about 28 ribs and about 1 1 spines on each 

 rib, so that the specimen probably possess more than 300 long 

 spines. This shews a great difference from Rhynch. senticosa. 



Localities. — Bradford Abbas, Broadwindsor, Oborne, and many 

 other places in Dorset ; also Milborne "Wick, near Galhanipton, 

 &c. (Somerset), also Dundry and near Bath (Somerset), Minchin- 

 hampton, and near Cheltenham (Gloucestershire), and in Nor- 

 mandy at Falaise, Moutiers, Port-en-Bessin, &c., and Dr. Oppel 

 says that its geographical range is very great, and that there is 

 scarcely a locality in the French, English and German inferior 

 or great oolite where it does not occur.* 



42. — Ehynchonella senticosa, v. Buck. 



1851. Ehynchonella senticosa, Davidson, Brit. Brach,, Palseont. 

 Soc, plate XV., fig. 21. 



1877. „ SENTICOSA, Davidson, Proceedings Dorset 



Club, Vol. I., plate iv., fig. 20. 



This species has by some authors been considered to be merely 

 a variety of Rhynch. s^nnosa, but I consider that there exists 

 very many differences between them. It is quite possible that 

 the rather finer ribbed variety of Rhynch. spinosa was mistaken 

 for Rhynch. senticosa. This species, however, differs from Rhynch. 

 spinosa in having the base of the valves nearly straight, the 

 beak rather raised so that the foramen can be easily seen, and a 

 vast number of extremely minute ribs covered with spines. 



Dimensions. — Length, Hi; breadth, 13; depth 8 lines. 

 Another specimen. — Length, 11 ; breadth, 12^; depth 7 lines. 

 On this last specimen I counted over 100 ribs on the lesser valve, 

 and about 40 spines on each rib. The specimen thus possessed 

 more than 4,000 spines on each valve. 



* Oppel Juraformation, p. 432. 



