SPIRIFERA. 55 



has been collected at BoUand, in the Craven district, at Malham Moor, Lowick, in the Isle 

 of Man, and in several parts of Derbyshire. In Scotland it occurs at Corieburn (Campsie) 

 at Westlothian and Bleith (Ayrshire). In Ireland, Mr. Kelly mentions Ballinacourty, 

 Armagh, and BallydufiF. On the Continent, it has been found at Vise, in Belgium, by 

 M. De Koninck, and at Keokuk, lovi^a (America) by Mr. Worthen. 



Spirieera iNTEGRicosTA, Phillips. Plate IX, figs. 13 — 19. 



GoNCHYLioLiTHUS ANOMiTEs- ROTUNDATUS {Martin) ? Petxificata Derbiensia, tab. 48, 



figs. 11, 12, 1809. 

 Spirifera INTEGRICOSTA, Phillips. Geol. of York., vol. ii, p. 219, pi. x, fig. 2, 1836. 



— ROTUNDATA {Martin), var. planata, Be Koninck. Animaux Fossiles de la Bel- 



giqiie, pi. xvii, fig. 4 (not Sp. planata, 

 Phillips). 



— PAUCicosTATA, M'Coij ? (British Palseozoic Fossils, p. 420, pi. 3, d, fig. 26, 1855. 



Spec. Char. Transversely or longitudinally oval, almost circular when young ; hinge 

 line shorter than the greatest width of the shell. The dorsal or dental valve is not quite 

 so deep as the opposite one, and ornamented by from twenty-one to twenty-five simple or 

 bifurcated rounded ribs, of which the three larger or central ones compose the mesial fold, 

 which is but slightly elevated above the regular convexity of the valve, except in the 

 vicinity of the front. Ventral valve convex, beak of moderate dimensions, proportions, 

 and incurvation. The surface is ornamented by from twenty to twenty-four rounded ribs ; 

 the mesial sinus extending from the extremity of the beak to the front, and varying both 

 in depth and width in different examples. Area wider than high, divided by a triangular 

 fissure partially covered by a pseudo-deltidium. Measurements taken from three examples 

 have produced — 



Length 15, width 14|, depth 11 lines. 

 „ J4, „ 18, „ 11 „ 

 Q Q ^ 



Obs. As I have already had occasion to remark, the principal, and indeed only 

 important difference between Sp. integricosta and S. ovalis consists in the mesial fold of 

 the first being divided by three or five longitudinal ribs, while in Sp. ovalis the same 

 portion of the shell is sharply defined, convex, and generally smooth, the contrast being 

 especially apparent in young shells. It has also appeared to me probable that Ayiomites 

 roiundatus of Martin,^ was founded on a young specimen of the species under descrip- 



' Martin describes liis species as follows: " Suborbiculatus longitudinaliter sulcatus, margine sinu 

 obsoleto. S. P. A fossil shell. The original an Anomia. Perforate valves convex, hinge straight, patulose 

 short ; foramen triangular. The general form of the shell somewhat orbicular and in a slight degree com- 

 pressed, as the convexity of the valves does not equal that which is found in other Auomitse of the same 



