. Bulletin of the Buffalo Society of Natural Sciences. Natural history; Science. Gems DIELASMA. ;. [Ety. : Di, two ; , lamella.] ()!) : Pioc. I)ul)lin Univ. Bot. Zool. Assoc, Vol. I., p. 260. 1898: Pal N. v., Vol. VIII., p. 2S»8.) Terebi-atnloid sliells, witli frequently a niediaii sinus in hotli valves. A large foramen and deltidial ])lates ai-e })res- ent. thoutih these latter may l)e oltseured by the incurvature of the beak. A large hinge jjlate, raised but little above the bottom of the valve, and sometimes actually adhering to it, and a relatively short brachidium, with a
. Bulletin of the Buffalo Society of Natural Sciences. Natural history; Science. Gems DIELASMA. ;. [Ety. : Di, two ; , lamella.] ()!) : Pioc. I)ul)lin Univ. Bot. Zool. Assoc, Vol. I., p. 260. 1898: Pal N. v., Vol. VIII., p. 2S»8.) Terebi-atnloid sliells, witli frequently a niediaii sinus in hotli valves. A large foramen and deltidial ])lates ai-e })res- ent. thoutih these latter may l)e oltseured by the incurvature of the beak. A large hinge jjlate, raised but little above the bottom of the valve, and sometimes actually adhering to it, and a relatively short brachidium, with a rather short recurvature of the ascending lamelhe, are characteristic internal featui-es. The sul>-genus ( Hall), was erected to receive such forms as Terebratula roinini>eri (Hall), in which the brachi- •bum is that of a Dielasma, but the hinge ])late reseml)les that of Crvptonella. I)lEL.\SMA (("'LXA) I;( ).M I.\( iERI. (Pal. X. Y., Vol. IV., p. 889, PI. LX.) Dis ting 11 is li in g Chnnicters.— Small size; ovate outline; trun- cated or slightly sinuate front; rounded cardinal slo})es; concentric . in- V\G. 149. Dielasma romiiigeri. Strue, which are often crowded mtO r)orsal. ventral, and profile views (from Hall). wrinkles near the fi-ont. Found in the Pleurodictynm beds and the Calcareous bed above, on the Lake Shore, and in Averv's Fiavine. Hall. (Fig. 141).). Genus TROPIDOLEPTrS. Hall. [Ety.: Tropis, keel; Icptos, slender.] (1857: 10th Ann. Rep't N. Y. State Cab. Nat. Hist., p. 151. 1898: Pal. N. Y., Vol. VIII., Pt. II., p. 302.) Shell coiicavo or plano-convex, with the hinge line much extended and straight, the whole aspect of the shell l)eing ''Strophomenoid" (ccjm])are Stropheodonta). In young shells the liinge line equals or exceeds in length the greatest width of the shell, but in mature shells it is shortei'. Pe(hcle. Please note that these images are extracted from scanned page images that may have been digitally enhanced for read
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