526 DR WHEELTON HIND ON 



Dimensions. — Fig. 23, PI. III., a bivalve example, measures : antero-posteriorly, 

 18 mm. ; dorso-ventrally, 13 mm. ; from side to side, 10 mm. 



Locality. — Scotland : Upper Bala beds of Drummuck ; Middle Bala, Shalloch Mill. 

 Ireland : Desertcreat, Co. Tyrone. 



Observations. — Portlock's type is a cast of the interior of a left valve. In the 

 Gray Collection is a fine bivalve shell with the test preserved, also a specimen which 

 shows the interior of the right valve. The characteristic shape of the shell is very 

 distinctive. The best-preserved specimens are from the Upper Bala beds, but I have 

 referred a number of specimens from the Middle Bala of Shalloch Mill to the same 

 species. These examples are crushed and distorted, but I note in some of them a 

 similar ornament to that I have observed in those specimens which were obtained at 

 Drummuck. 



Genus PalsBoneilo, Hall, 1885. 



Palieoneilo, Hall, 1885, Oeol. Surv. New York, Pal., vol. v., pt. i., Lamell., ii., p. xxvii. 

 Hind, 1900, Q.J.G.S., vol. lvi. p. 46. 

 „ „ 1904, Mono. Brit. Carb. Lamell. (Pal. Soc), p. 140. 



Generic Characters. — " Nuculiform shells, transversely ovate or subelliptical, the 

 posterior end often subrostrate ; well or more or less defined sulcus along the umbonal 

 slope. Surface marked with striae of growth, which are often lamellose and elevated 

 into concentric ribs. Hinge furnished with a row of regular small transverse teeth, 

 which is sometimes interrupted beneath the beak by a change in the direction of the 

 teeth or by several oblique teeth. Ligament external, contained in a shallow and 

 narrow groove along the cardinal border. Muscular scars not strongly impressed, 

 situated below the extremities of the hinge line. Pallial line simple." 



I have quoted Hall's diagnosis, and would refer to my monograph, op. supra cit., 

 for a discussion on the subject. 



Palaeoneilo antiqua, sp. nov. (PI. III., fig. 28.) 



Specific Characters. — Shell small, inequilateral, transverse, elliptical. Anterior end 

 broad, posterior narrowed, shell compressed. Anterior margin rounded ; the inferior 

 very convex, the segment of a larger circle than the anterior border. The posterior 

 border narrow, bluntly rounded. The hinge line arched, the posterior portion sloped 

 downwards rapidly. The umbones are obtuse, narrow, directed forwards and incurved, 

 placed very far forwards. There is a very broad and deep escutcheon, separated from 

 the dorsal slope by a raised, erect, narrow ridge. 



Interior. — Not observed. 



Exterior. — Surface without any ornaments. The periostracum appears to have 

 been thick. 



Dimensions. — Fig. 28, PI. III., a left valve, measures : antero-posteriorly, 16 mm. ; 

 dorso-ventrally, 10 mm. 



