NUCULANA STILLA. 201 



M' Coy's shell as a synonym of N. attenuata. Similarly it is impossible to tell, 

 from the specimen of N. longirostris, M'Coy, preserved in Dublin, whether or no 

 this shell really belongs to N. attenuata or to N. Sharmani, as nothing is to be seen 

 of the escutcheon, and no mention is made of this part of the shell in the 

 description. Under the circumstances, therefore, the name N. Sharmani, 

 R. Btheridge, jun., is retained. It is curious, however, when contrasting his 

 shell with several others from M'Coy' s work, that Mr. Etheridge did not perceive 

 any similarity between his shell and N. longirostris. 



Noculana stilla, M'Coy, sp., 1844. Plate XV, figs. 23—25, 44—46, 46 a. 



Nucula stilla, M'Coy, 1844. Synops. Carb. Foss. Ireland, p. 71, pi. xi, fig. 18. 

 Leda stilla, d'Orb., 1850. Prodrome paleontologie, p. 129. 

 — Tbaquairi, B. Etheridge, jun., 1876. Ann. Mag. Nat. Hist.,ser. 4, vol. xviii, 



p. 100, pi. iv, fig. 4. 

 Ctenodonta stella, Bigsby, 1878. Thesaur. Devonico-Carb., p. 303. 

 Nttcula stella, Etheridge, 1885. British Fossils, part 1, Palaeoz., p. 287. 

 Nuculana Tbaquairi, Etheridge, 1885. Ibid., p. 288. 



Specific Characters. — Shell clavate, gibbose, short, and arcuated. The anterior 

 end forms the greater portion of the shell, though in a transverse direction the 

 posterior portion of the shell is slightly longer than the anterior. The anterior 

 border is broad and rounded, passing with a gradual curve into the inferior 

 border, which is convex downwards ; the posterior portion rises rapidly, and is 

 almost straight. The superior border consists of two portions, inclined at a very 

 obtuse angle, which meet under the umbo. The posterior portion is often 

 hollowed and depressed, so that the posterior border is very narrow and bluntly 

 pointed. The umbones are just anterior to the centre of the shell, and directed 

 backwards ; they are small, tumid, and elevated. Proceeding downwards and back- 

 wards from the upper edge of the umbo to the apex is a sharp ridge, concave in 

 outline upwards, which marks off the surface of the shell from the broad 

 escutcheon. The valves are equally and regularly swollen for the greater part, 

 but compressed posteriorly. 



Interior. — Unknown. 



Exterior. — The surface is ornamented with regular, equal, flattened, concentric 

 striae, which terminate abruptly near the narrow posterior end, which has much 

 finer markings. 



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