﻿SCABILE. 



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in ferruginous concretionary masses derived from the bed No. 45 of Dr. Fitton's 

 elaborate and valuable stratigraphical Table above referred to ; the position of this bed is 

 nearly at the upper boundary of the Neocomian formation. Another locality is Seend, 

 near Devizes, in a similar stratigraphical position. 



Trigonia Meyeri, Lye, sp. nov. Plate XXIII, fig. 6. 



Shell ovately trigonal, very convex anteally, attenuated and compressed posteally ; 

 umbones large, elevated, antero-mesial, pointed, much recurved ; anterior side produced, 

 its border rounded and curved with the lower border, which becomes nearly straight 

 posteally near to the attenuated extremity ; the superior border is much excavated and 

 lengthened, terminating posteally abruptly, forming nearly a right angle with the siphonal 

 border, which is nearly perpendicular, its height scarcely exceeding one fourth the height 

 of the valves. The area is narrow, much curved, slightly elevated, separated from the 

 other or pallial portion of the valve by a distinct narrow divisional angle or slight ridge ; 

 this does not rise higher than the surface of the area, which is delicately transversely 

 lineated over its posteal half, and traversed by a distinct longitudinal mesial furrow ; the 

 anteal portion of the area is traversed transversely by a numerous series of small, closely 

 arranged, wrinkled costellae, which pass also without interruption across the larger 

 escutcheon. The upper surface of the valve is almost entirely occupied by a large, 

 concave escutcheon, which is conspicuously costellated transversely throughout its length ; 

 its breadth exceeds that of the area, from which it is separated only by a faintly elevated 

 ridge. The larger or pallial portion of the valve has a series of about twenty-six rows of 

 small, closely placed, rounded, and slightly crenulated costae, all of which originate at the 

 carinal angle of the valve and pass downwards nearly perpendicularly ; the more posteal 

 ten rows occupy the more flattened or depressed portion of the surface, they enlarge 

 slightly near to the lower border ; the other or more anteal rows form a sudden flexure 

 about their middle portions, where they also enlarge as suddenly and pass forwards 

 almost horizontally to the anterior border, becoming somewhat curved and attenuated at 

 their anteal extremities. The anteal or pedal border has upon its upper half a closely set 

 series of small, oblique, supplementary costellae, two of which occupy each of the inter- 

 costal spaces to the number of nine spaces. 



This is one of the more inflated of the aliformis group, the great convexity, as in that 

 species, being limited to the anteal third of the shell ; the sudden flexure of the costae at 

 that part and their attenuation upwards to the angle of the valve are very conspicuous 

 features and distinguish it from all others of the Scabra, including T. aliformis, which, 

 with fewer costae, has also a smaller flexure and much less abrupt ; the anteal varices are 

 also much fewer, more oblique, and more inflated. 



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