7<i CARBONIFEROUS LAMELLIBRANCHIATA. 



between each original pair a short distance from the umbo. I cannot make out 

 the ribs to be nodulose, but they are often imbricate near the lower margin. The 

 ribs are present over the posterior ears, but less marked, and are crossed by 

 subimbricating concentric lines. 



In the right valve the radiating ribs are more numerous and finer, and almost 

 obsolete radiating ribs are seen on the posterior ear. The anterior ear is con- 

 centrically striated. 



Dimensions. — PI. XVII, fig. 29, a right valve from Millicent, co. Kildare, in 

 the AVoodwardian Museum, Cambridge, measures — 



Antero-posteriorly . . . .42 mm. 



Dorso-ventrally . . . .35 mm. 



Localities. — Ireland : the Carboniferous Limestone of Millicent, co. Kildare ; and 

 Castleconnell, Doohylebeg, and Gortnagrour, co. Limerick. 



Observations. — Two shells, a right and left valve, labelled Pecten fallax, are in 

 the Griffith Collection, Museum of Science and Art, Dublin. It seems to me 

 possible that these two specimens may not have originally served as M'Coy's types. 

 They are very poor specimens. The figures must have been largely hypothetical, 

 which to some extent may account for their partial inaccuracy. Although the 

 contour and the hinge-line are correctly drawn in both figures, these details are 

 not shown in the shells. The ears of both valves are well defined and marked off 

 from the valve by an acute angular fold, a character not indicated in M'Coy's 

 figures, and I am unable to see the nodulose character given to the ribs of the left 

 valve in the plate in the (?) original specimen, or in any others which I have 

 examined. 



I figure in PI. XVII, figs. 28—30, the cast of the interior of right and left 

 valves from the collection of the Geological Survey of Ireland, and a fairly 

 perfect right valve in the collection of the Woodwardian Museum, Cambridge. 



AVICTJLOPECTEN SUBCONOIDETJS, I! . Kllieriihjr, Jan., 1870. Plate XVII, figs. 1 — 5. 



Aviculopecten subconoidetjs, B. Etheridge, jun., 1870. Aim. Mag. Nat. Hist., 



ser. 4, vol. xviii, p. 96, pi. iv, figs. 1,2. 



Specific Characters. — Shell of medium size, ovato-quadrate, antero-posterior less 

 than the dorso- ventral diameter. The left valve convex, the right valve flattened. 

 Tlic cars moderately well defined, except the right anterior ear, which is very well 

 marked. The anterior margin sinuous, the inferior broadly curved, the posterior 

 sinuous. The hinge-line straight, not quite as long as the greatest antero-posterior 

 diameter. The umbones small, compressed, flattened, placed a little in front of 



