30 NOTES ON THE BRITISH JURASSIC BRACHIOPODA. 



L. oralis, Sow., Kim. clay, Weymouth. 



L. sacctilus, Dewalque, Middle Lias, Batliford, near Bath. 



This ought to stimulate us in this district to search for 

 some of these species, especially for L. davidsonij brodiei, 

 and heanii. 



The first of these, L. davidsoni, named by Oppel, Davidson 

 never saw, while L. brodiei was named by Davidson from an 

 incomplete single valve found by the Rev. P. B. Brodie. 



DISCINA, Lamarck, 1819. 

 Etym. — Discus, a disk. 



Like the Lingulee, the shell in this genus is of a horny 

 animal substance, inarticulated, and destitute of shelly 

 supports or loop for the labial appendages. It is more or 

 less orbicular in shape, and the upper or dorsal valve being 

 somewhat conical gives a patelloid or limpet-like appear- 

 ance to the shell. 



The lower or ventral valve is depressed, flat, or slightly 

 convex, and is affixed to submarine objects by a tendinous 

 peduncle issuing through a small slit or fissure (foramen), 

 varying in length and size, extending from its centre to near 

 the margin (7, p. 9). 



The peduncle is so short that the shell appears to be 

 attached by the ventral valve or some portion of its sub- 

 stance, as in Crania. 



This is the most persistent of all our British fossil 

 Brachiopoda ; if we include in this genus those shells now 

 called Discinisca, it has been found in all the geological 

 formations, from the Silurian up to existing seas, where it is 

 represented by some seven or eight species. 



From what we know of the recent Discinse and Lingulse 

 it is generally supposed that the rocks in which the fossil 



