86 BRITISH OOLITIC AND LIASIC BRACHIOPODA. 



what we observe in B. serrata. I am not acquainted with any specimens exactly similar 

 to our English type from the Continent, although I found in the Lias of Fontaine-Etoupe- 

 four, in Normandy, some examples approaching to B. serrata, and of which they may perhaps 

 be a variety. 



Plate XV, fig. 1 . From a specimen in the collection of Mr. Moore. 

 „ fig. 2. An elongated variety from my collection. 



80. Rhynchonella plicatella, Sow. Sp. Plate XVI, figs. 7, 8. 



Terebratula plicatella, Sow. 1825. Min. Con., vol. v, p. 167, tab. 503, fig. 1. 



— — Von Buck, 1834. Uber Terebrateln ; et Mem. de la Soc. G6ol. 



de France, 1838, vol. iii, 1st ser., p. 146, pi. xv, fig. 17. 



— — Deshayes, 1836. Nouv. Ed. de Lamarck, p. 355. 

 — . — Deslonffchamps, 1837. Soc. Linn, de Normandie. 



— — Morris. Catalogue, 1843. 



— — Tennant. A Stratigrapbical List of Brit. Fossils, 1847, p. 74. 



— — Bronn. Index Palseont., 1848, p. 1246. 

 Rhynchonella plicatella, D'Orbigny, 1849. Prodrome, vol. i, p. 286. 



Diagnosis. Shell inequivalve, subtrigonal, sub-globose, longer than wide ; perforated 

 valve, shallow and depressed, less convex than the other; front semicircular, beak acute, not 

 much produced, tapering, more or less recurved; foramen small, entirely surrounded by the 

 deltidial plates ; beak ridges sharply defined ; a slightly concave false area existing between 

 them and the hinge margin, a similar depression being likewise visible on either side of the 

 umbo, giving to this portion a pinched appearance ; the hinge-line greatly indenting the 

 imperforated valve, which is regularly convex, and nearly three times as deep as the rostral 

 one ; surface ornamented by a variable number of plaits, from twenty-six to fifty on either 

 valve ; rarely any distinct mesial fold or sinus. Some of the costse bifurcate at a short 

 distance from the beak and umbo; structure imperforated. Length 18, breadth 17, 

 depth 13 lines. Some examples attain even larger dimensions. 



Obs. This species belongs to the Inferior Oolite of Chideock, near Bridport, whence 

 the original specimen figured and described by Sowerby was obtained by Sir H. de la Beche, 

 and is now deposited in the Museum of the Geological Society; since that period it has 

 been found in several other localities, such as at Dundry and Dinnington. On the 

 Continent very fine specimens are found at Moutiers, Bayeux, and other places in France; it 

 was erroneously considered by Defrance 1 to be the same as Ter. multicarinata, Lamarck, 

 which is quite another species. 2 B. plicatella is well characterised, and does not seem to 

 vary in general as much as some others, although, in its details, it is often very different, 

 from the variable number of its plaits, and in the young state it is very much elongated, as 



1 Die. Hist. Nat., vol. liii, 1828, p. 137. 



2 Davidson's Notes on an Examination of Lamarck's Species of Fossil Terebratulse. 'An. and Mag. of 

 Nat. Hist.', vol. v, 2d ser., 1850, PI. xiv, fig. 37. 



