500 DR WHEELTON HIND ON 



Genus Gosseletia, Barrois, 1881. 



Gosseletia, Barrois, 1881, Ann. Soc. Geol. du Nord, vol. viii. p. 176. 



,, Hall, 1884, Geol. Sum. N. York, Pal., vol. v. pt. i., Lamellibr., p. xiv. 

 „ Miller, 1889, N. Amer. Geol. and Pal, p. 482. 



Generic Characters. — Shell subtriangular, truncate on anterior side, subalate 

 posteriorly. Ligamental area wide, longitudinally striate ; cardinal teeth below the 

 beak strong ; lateral teeth elongate ; surface with concentric strise. 



Observations. — This genus was erected for a modioliform shell with cardinal and 

 lateral teeth and a striate ligament, from the Devonian of Spain. Hall referred two 

 specimens to the genus from the Hamilton group of New York, a member of the 

 Devonian series of that State. The shells that I now refer to the genus are from the 

 Upper Bala and Llandovery beds of Scotland, in which I consider it is represented by 

 two species. Unfortunately, specimens are not numerous. 



Gosseletia ponderosa, sp. nov. (PI. III., figs. 1, la, lb.) 



Specific Characters. — Shell of medium size, obliquely subquadrate ; extremely 

 gibbose in front, subalate posteriorly. The anterior end obsolete. The anterior 

 margins adpressed to form an oblique broad anterior surface, so impressed below the 

 beaks as to be concave. The inferior margin is rounded ; the posterior obliquely 

 truncate, almost straight. The postero-superior angle well marked, obtuse. The hinge 

 line of only moderate length, straight. The umbones are swollen, pointed, elevated, 

 directed forwards terminally, widely separated by a broad striate ligamental area. 



Interior. — No details exposed. 



Exterior. — The surface is ornamented with fine concentric lines of growth, with an 

 occasional deep, narrow, concentric sulcus. 



Dimensions. — Fig. 1, PI. III., measures : antero-posteriorly, 34 mm. ; dorso-ventrally, 

 51 mm. ; from side to side, 38 mm. 



Locality. — The Star-fish bed, Upper Bala. 



Observations. — A single fairly perfect specimen, on which I have founded the 

 species, occurs in the Star-fish bed. The specimen consists of a complete cast of the 

 interior and a mould of the external surface. The hinge plate is not well enough pre- 

 served to show any of the hinge teeth. It could hardly be mistaken for the species 

 which is found higher up in the Llandovery beds, the latter being much more com- 

 pressed, with a totally different anterior end. 



Gosseletia antiqua, sp. nov. (PI. III., figs. 2, 3.) 



Specific Characters. — Shell of medium size, obliquely ovate, triangular and gibbose. 

 The anterior end almost obsolete, narrow, its margin rounded. The inferior border 

 almost straight, descends downwards and backwards. Postero-inferior angle bluntly 

 rounded. The posterior border is elongate, gently convex. Hinge line straight. 



