50 BRITISH CRETACEOUS BRACHIOPODA. 



levels, and often, though close at their origin, diverge while others converge, so that notwith- 

 standing that the greater number follow the same direction, they are not individually 

 parallel to each other. We regret not having been able to examine the interior of this 

 form, which we suppose different from that of true Terebratula, but with which it*had better 

 remain till further investigation. 



T. rugulosa has been found in England by Messrs. Moore, Bunbury, and Pratt, in the 

 Chalk with green grains at Chard Chadstock and Chaldon along with T. ovata. In France 

 I have found it in great numbers at Rouen, in beds of the same age. 



Plate IV, fig. 14. A specimen, natural size, from the collection of Mr. Moore. 

 „ fig. 14 d . Another specimen, enlarged, in my collection. 



19. Terebratula squamosa, Mantell. Plate V, figs. 5 — 11. 



Terebratula suuamosa, Mantell. Geol. of Sussex, p. 132, 1822. 



— — Morris and Dav. Annals and Mag. of Nat. Hist., vol. xx, 



p. 254, pi. xviii, fig. 8"\ 1847. 

 disparialis (pars), D'Orb. Pal. Franc. Ter. Cretace'es, vol. iv, p. 100, 

 pi. 512, figs. 16, 17, (not figs. 12, 13, which belong to 

 T. rugulosa,) 1847. 

 squamosa, Bronn. Index Pal., p. 1251, 1848. 



Diagnosis. Shell orbicular, or somewhat longitudinally ovate, valves nearly equally 

 convex, sometimes gibbous ; beak moderately produced and obliquely truncated by a 

 circular entire foramen ; deltidium small, rather dilated at the base, the convexity of the 

 valves is at times equal to the front, while in other specimens there exists in the anterior 

 portion of the imperforated valve a longitudinal depression and tendency to biplication. 

 Surface marked with concentric squamose ridges, crossed by numerous radiating zig-zag 

 raised striae, giving to the squamae an irregular serrated appearance ; structure punctuated, 

 punctse rather widely separated ; interior unknown. Dimensions variable, the largest 

 specimen as yet discovered measuring, length 15, width 12, depth 9 lines, but the average 

 size is, length 7, width 6, depth 5^ lines. 



Obs. This species was described in 1822 by Dr. Mantell, who found it in the Gray 

 Marl, of Hornsey. It is a form well known in England, but not having been illustrated 

 by that celebrated geologist, Mr. Morris and myself thought it advisable to re-describe and 

 figure the species in the ' Annals,' 1847 ; about this period or later M. D'Orbigny published 

 the same shell under the name of T. disparialis, associating with it another form which we 

 separate. Since that period the discovery of a great many British specimens in different 

 localities allow us to notice several of its most important variations, and which are illus- 

 trated in Plate V. Dr. Mantell was provided only with small and young specimens, fig. 5 

 of our Plate ; but Mr. Cunnington discovered at Pottern Butts, in the Upper Green Sand, 

 specimens attaining much larger dimensions, as may be seen by figs. 8 and 9. In a few 

 adult individuals there exists a tendency to biplication ; a character which to that extent 



