TEREBRATULA. 37 



Terebratula numismalis, Zieten. 1832. Wurtemb. Verst., pi. xxxix, fig. A. 



— orbicularis, Zieten. 1832. Wurtemb. Verst., pi. xxxix, fig. 5. 



— numismalis, Bronn. Leth. Geog., pi. xviii, fig. tf. 



— — Beslongchamps. 1837- Soc. Linn, de Normandie. 



— V. Buck. 1838. Mem. Soc. Geol. de France, vol. iii, 



l" re Serie, p. 191, pi. xvii, fig. 4. 

 _ — Bruyere. Ency. Meth., p. 240, fig. 1. 



— Quenstedt. 1843. Das Flos. Wurt., pp. 183, 184. 



— D'Orb. Prodrome, vol. i, p. 240, 1849. 



— — Dav. 1850. Lamarck's Species, Annals and Mag. of Nat. 



Hist., vol. v, 2 de Serie, pi. xiii, fig. 17, and pi. xv, fig. 22. 



Diagnosis. " T. testa subrotundd lavi, utraque valvd superne sinu instructd : striis 

 concentricis remotis : nate brCvi : foramine minimo." — (Lamarck.) 



Shell inequivalved, depressed, nearly circular or slightly pentagonal, notched in front, 

 variable in its contour ; valves nearly equally convex, much depressed and flattened, surface- 

 smooth, the margin of valves forming almost a straight line ; beak slightly compressed 

 and keeled, lateral ridges of beak continued along the side, without recurving, to 

 join its margin ; false area, very small and well defined ; deltidium in two pieces, wide at 

 the umbo, diminishing as it reaches the foramen, which is entire and remarkably small. 

 Sometimes a slight central depression or sinus is visible on each valve ; lines of growth 

 strongly marked, punctuation very fine. Loop free, attached only to the crural base, and 

 extending nearly the whole width of the shell ; mesial plate well defined. Length and 

 width on an average nearly the same, from 11 to 13 lines, depth from 4 to 6. 



Obs. This species was first brought into notice by Lamarck, who pointed out its 

 extremely small area and foramen ; it is easily distinguished from all other liasic and oolitic 

 Terebratulae by its extreme flatness. Lamarck and Valencienne's Ter. cor., as I stated in 

 the 'Annals of Natural History,' of June, 1850, is a synonym of this species, established on 

 a specimen bearing accidentally the shape of a heart, and is only one of the numerous 

 variations in contour, observable in Ter. numismalis, as may be seen from some of the forms 

 illustrated in Plate HI, figs. 4 — 9. This species is very abundant in the highest beds of 

 the middle and upper Lias, and it is only within a few years that it was discovered 

 in England, in the neighbourhood of Cheltenham, where the specimens have a dark 

 grayish colour. Mr. Walton and I found it two years ago in the neighbourhood of 

 Radstock, and at Farington Gurney, where they are yellowish, owing to the colour of the 

 clay in which they are imbedded ; and many fine specimens are to be seen in the Collections 

 of Dr. Wright, Professor Buckman, and others. It was also obtained by Mr. Hugh 

 Miller, from the Lias of Shendwich, in Scotland. Plate V, fig. 8, illustrates a specimen 

 from that locality. In France it is very common, about Eurecy, Landes, Vieux Pont, 

 St. Armand, Pouilly, Avallon, Lyon, &c, where larger and finer specimens than any 

 of our British ones have been found, and they may be viewed in the Collections of 

 M. Deslongchamps, of Caen, who kindly lent me the specimens illustrating the internal 



