AVKTLOI'ECTEN FLMMJLVITS. 93 



AVICULOPECTEN QU1NQUELINEATUS, M'Coy, Sp., 1844. 



Pecten quinquelineatus, M'Ciiy, 1814. Synops. Carb. Foss. Ireland, p. 1)8, 



pi. xvii, fig. 6. 



Specific Characters. — Shell largo, orbicular, right valve only slightly convex- 

 The lower margin almost circularly rounded. Ears and hinge-line unknown. 



Interior. — A large posterior adductor scar in the normal position. 



Exterior. — The surface is ornamented with many narrow, uneven, radiating 

 ridges, between each pair usually fine, smaller, radiating striae, the middle one of 

 which is largest ; interstitial spaces flat. 



Localiti/. — Ireland : the Carboniferous Limestone of Mohill, co. Leitrim. 



Dimensions. — Too imperfect to measure. 



Observations. — The species was founded on a fragment of a left valve, the ears 

 and upper part of which were absent. The type is present in the Griffith 

 Collection, Museum of Science and Art, Dublin ; hence I have retained the species. 

 The ornamentation is very like that of A. interstitialis in the adult form, but the 

 fragment is much too flat for this species. Possibly a specimen will some day be 

 found showing the real affinity of this shell and its value as a species. It is to be 

 noted that M'Coy's figure shows three smaller radiating ribs between each pair of 

 large ones, not, as he states, five. 



Aviculopecten fimbriatus, Phillips, sp., 1836. Plate XII, figs. 12, 13. 



Pecten fimbriatus, Phillips, 1836. Geol. Yorks., pt. ii, p. 213, pi. vi, fig. 28. 



Specific Characters. — Shell of medium size, both valves very moderately convex, 

 the right very little the less so, ovato-orbieular. The hinge-lino short and straight. 

 The umbones central, pointed, moderately swollen. The anterior ears .short, 

 depressed, well marked off from the rest of the valve, with a slit below the right 

 anterior ear for the byssus. The posterior ears small, depressed, well defined, the 

 sharp margin from the umbo to the anterior border somewhat concave upwards. 



Interior. — Smooth. The decorticated shell shows many radiating and concen- 

 tric ribs. 



Exterior. — The surface is ornamented with many sinuously imbricate, concentric 

 ridges, and similar radiating ribs, which give rise to a cancellated appearance in 

 the right valve, the concentric markings being less rugose and somewhat more 

 regular. The ears appear to be almost smooth. 



