TEREBRATULA. 49 



Plate IV, fig. 10. Another more adult shell from the same bed and locality, also from 



the collection of Mr. Moore. 

 „ fig. 11. A very adult specimen from the Upper Green Sand, near Warminster, 



in the collection of Mr. Cunnington. 

 „ figs. 12, 13. Two exceptional shapes, likewise from the same locality and 



collection. 



18. Terebratula rugulosa, Morris. Plate IV, figs. 14, 14". 



Terebratula rugulosa, Morris. Amials and Mag. of Nat. Hist., vol. xx. p. 253, 



pi. xviii, figs. 5, a"% 1847. 

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



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

 to T. squamosa of Mantell,) 1847. 



Diagnosis. Shell ovate or somewhat irregularly pentagonal, longer than wide, 

 straight or slightly indented in front ; valves almost equally convex, dental one most so ; 

 a small depression existing near the front in some specimens, the margin of smaller valve 

 slightly underlying the perforated one ; beak rather produced, not much recurved, obliquely 

 truncated by a large circular foramen ; deltidium small, in two pieces, partly surrounding 

 the foramen ; beak ridges moderately distinct. Surface covered by minute ruga?, and in 

 general the middle portion of each valve longitudinally, and but little interrupted. Those 

 on the side diverge and have a tendency to break into small oblong tubercules, slightly 

 projecting sometimes in the form of short spines. Structure distinctly and thickly punc- 

 tuated. Interior unknown; dimensions variable; length 11, width 8, depth 7 lines. 



05s. This form was described and figured by Mr. Morris and myself, in 1847, 

 under the name of T. rugulosa; a little later it received from M. D'Orbigny that of 

 T. disparialis, but the last-named author includes in his species another form which 

 we consider distinct and known in England under the name of T. squamosa (Mantell,) the 

 surface being ornamented by wavy striae and numerous squamose concentric lines of growth. 

 Both Ter. rugulosa and squamosa occur in great numbers in the Chloritic Chalk of Rouen, 

 and seem to me always easily distinguished : in England they are equally distinct, and 

 separable from T. ovata, the last being much more convex, and deprived of that remarkable 

 longitudinal depression in the smaller valve, and the corresponding keel-shaped projec- 

 tion in the larger one ; in T. rugulosa the convexity extending in most cases regularly to 

 the front, where sometimes a wide but slender depression is seen, quite different from that 

 observable in T. ovata, and confined to the margin; by its exterior ornaments it approaches, 

 however, to Ter. ovata, as justly observed by M. D'Orbigny, but the general aspect of the 

 shell is otherwise quite different. Both species may, therefore, for the present, be conve- 

 niently retained under distinct appellations ; the irregular manner in which the tubercules 

 are disposed is very remarkable; some are shorter and wider than others, arising at different 



