47 
On the Brachiopoda recently discovered in the 
Yorkshire Oolites. 
By John Francis Walker, M.A., F.G.S. 
Since my former communication to this Society in the 
Report for 1889, I have been able to add to the list of 
Yorkshire Brachiopoda, Thecidium ornatum , Moore, and a 
variety of Terebratulwa substriata, Schlotheim ; a short account 
of these discoveries appeared in the Geological Magazine for 
1892. I now give further notes on these species and references 
to their chief literature. 
Thecidea ornata, Moore. 
ihecidimn ornatum —Moore, 1861. 
The Geologist, vol. iv., page 96, plate ii., 
figure 1—3. 
Thecidium ornatum —Davidson, 1876. 
Suppl. to Jurassic Brachiopoda, page 
104, plate xiii., fig 5—9. 
Theciiium ornatum —J. F. Walker, 1892. 
Geological Magazine, page 548. 
As this genus was named Thecidea by Defiance, and this 
name is used by the continental Geologists, I think it 
advisable to use it for the sake of uniformity instead of 
Thecidium , a name afterwards given to it by Sowerby. 
Thecidea ornata is so well described by Davidson in the 
supplement to his monograph on Jurassic Brachiopoda, that it 
is unnecessary here to do more than refer to that publication. 
I have obtained a considerable number of specimens of 
Thecidea ornata , Moore, from the Coral rag in the bed containing 
Phasianella , (Pseudomelania) striata, Pseudodiadema versipora , 
Hemicidaris intermedia. They are from a quarry between Ayton 
and Scarbro’, where they are very plentiful, especially the dorsal 
valve; but it is troublesome to find on account of its small size; it 
is best obtained by washing the marl and then carefully sifting 
it; occasionally it is found attached to Ostrea. Since I sent 
an account of this discovery to the Geological Magazine, I have 
been able to obtain specimens of this shell from some marl of a 
