﻿JURASSIC AND TRIASSIC BRACHIOPODA. 85 



Three not quite perfect examples of this minute shell were found by Mr. Moore in 

 the Inferior Oolite of Dundry, where it appears to he rare. 



15. Discina ? Moorei, Dav. Sup., PL X, figs. 14, 14 a. 



Of this minute species I have seen but a single example, which was found by Mr. 

 Charles Moore in the Upper Lias near llminster. 



It is almost circular and conical, with vertex subcentral. The exterior surface shows 

 numerous minute radiating lines or small ribs. 



16. Discina Holdbni, Tate. Dav., Sup., PI. X, figs. 12 and 12a (7, 8?), and PI. XI, 



fig. 32. 



Discina, sp., Terquem et Piette. Lias inf. de l'Est de la France, p. 113, tab. xiv, 



figs. 33, 34, 1865. 



— Holdeni, R. Tate. Quart. Journ. Geol. Soc, vol. xxiii, p. 314, 1867 ; 



Geol. Mag., vol. vi, p. 553, 1869 ; Appendix 1, a list 

 of the Irish Liassic Fossils, p. 23, Belfast Natu- 

 ralists' Field Club, September, 1870. 



" Shell small, regularly conical ; base orbicular, the length and breadth in the propor- 

 tion of about 5 to 4 ; summit central ; test concentrically striated ; colour black or 

 brownish -black ; yellowish-brown in the young shell. Dimensions of an average-sized 

 specimen — diameter (long) 4 - 5 and (short) 3"6 millimetres ; height 2"3 millimetres. 

 This form is distinguished from other Liassic species by its regularly conical form and 

 central apex ; and it is readily separated from D. reflexa, Sow., by the latter character." 

 Geological position. — Ranges from the zone of Ammonites angulatus to that of Ammonites 

 Ibex, and throughout the Lower Lias in the east of France. " 



I have reproduced Mr. R. Tate's description of this species, as he is better acquainted 

 with the species than myself, and because I cannot always discriminate between specimens 

 of this species and of D. reflexa, of the same dimensions, and in which the position of 

 the summit or apex differs considerably. Mr. R. Tate informs me that in his original 

 description he takes for the type of his species figs. 32 — 34 of pi. xii of Terquem and 

 Piette's Lias inf. de l'Est de la France, that possibly Orbiculoidea Charmassei, d'Orb., Prod, 

 p. 222 is the same shell. " Espece de moyenne taille, a sommet subcentral, ce qui la 

 distingue de V O.Babeana, d'O., Lias, Avallon but that there is an insufficiency of descrip- 

 tion to make the identification absolute. I may also observe that in recent species of 



