. The Canadian naturalist and geologist. Natural history -- Periodicals. Silurian Fossils of Canada, 55 Strophomena Leda. N. Fig. 2. Fig. 3. Fig. 2.—Stropho7nena Leda with a portion of the hinge area of the ven- tral valve enlarged to shew the striated teeth. 3.—A specimen without ears supposed to be of the same species. Description,—Shell rather small and thin, semi-oval, the front and front angles regularly rounded, sometimes a little narrower at the base of the ears than at one third the length from the hinge line, the latter usually exceeding the greatest width of the shell, and formin
. The Canadian naturalist and geologist. Natural history -- Periodicals. Silurian Fossils of Canada, 55 Strophomena Leda. N. Fig. 2. Fig. 3. Fig. 2.—Stropho7nena Leda with a portion of the hinge area of the ven- tral valve enlarged to shew the striated teeth. 3.—A specimen without ears supposed to be of the same species. Description,—Shell rather small and thin, semi-oval, the front and front angles regularly rounded, sometimes a little narrower at the base of the ears than at one third the length from the hinge line, the latter usually exceeding the greatest width of the shell, and forming projecting spiniform ears. Width excluding the ears, five to nine lines ; length five-sixths of the width ; ears one line and a half in length each, in a well preserved specimen five lines wide. The ventral valve is in the small specimens, depressed convex and nearly uniformly arched from beak to front; the umbo well defined, but the concave depressions on each side rather obscure; no deflected margin. The large specimens (nine lines wide) are sometimes strongly convex. Dorsal valve concave, its curvature corresponding to that of the ventral valve. Surface as in S. alter- nata. Area of ventral valve half a in line height in a specimen seven lines wide, lying nearly in the plane of the margin, apparently a little sloping outwards, forming an angle of about 100° with that of the dorsal valve, which latter is scarcely one-fourth of a line wide. Foramen not distinctly observed but apparently wider than high. The detached and empty ventral valves exhibit two rather large triangular hinge teeth, one on each side of the foramen, covered with stri£e on the outside in a manner similar to that of the area of those species to which Professor Hall has given the generic name of Strophodonta. The spiniform ears are often either broken or worn away. Varieties.—Several specimens nine lines wide without ears, and others of the same size strongly convex, and with an indis-. Please no
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