46 DE. WHEELTON HlND ON THE OCCTJEKENCE OP [Feb. I9OO, 



5. On the Occuerence in British Carboniferous Bocks of the 



Devonian Genus Palceoneilo, with a Description of the New 

 Species P. cambonifera. By Dr. Wheelton Hind, B.S., 

 E.R.C.S., F.G.S. (Read December 6th, 1899.) 



The genus Palceoneilo was established by Hall for certain Nuculi- 

 form shells from the Devonian beds of New York. He selected as 

 the type Palceoneilo constricta, which had hitherto been referred to 

 the allied genus Nuculites by Conrad. 



The diagnosis of the genus was as follows : — 



4 Nuculiform shells, transversely ovate or subelliptical, the pos- 

 terior end often subrostrate, with a more or less defined sulcus along 

 the umbonal slope. Cardinal line arcuate. Surface marked with 

 striae of growth, which are often lamellose and elevated into con- 

 centric 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.' 

 Hall referred twenty species to this genus. 



The Nuculidae are represented in Carboniferous rocks by the 

 genera Nucula, Nuculana, and Ctenodonta, and to these must now 

 be added Palceoneilo. Two fine examples of this genus are in the 

 Museum of Practical Geology, Jermyn Street, labelled 'Carboni- 

 ferous Shale (bottom of Yoredale Shale), beck south of Hammerton 

 Hall, Slaidburn, Yorkshire,'* which I think means that the shells 

 occur above the massif of Mountain Limestone, at which horizon 

 the allied genus Ctenodonta also occurs. 



It is therefore curious that a genus so well developed in Devonian 

 times should appear at the top of the Carboniferous Limestone 

 Series, there being no trace of its existence in intermediate beds. 

 It is also noteworthy that the species attains considerable size, and 

 is remarkably well developed, the shell possessing all the distinctive 

 characters of the genus. 



Genus Paljsoneilo, Hall, 1870. 



1842. Nuculites, Conrad, Journ. Acad. Nat. Sci. Philad. vol. viii, p. 249. 



1858. Leda, Stevens, Amer. Journ. Sci. sen 2, vol. xxv, p. 262. 



1870. Palceoneilo, Hall, 'Prelim. Notice Lamellibr. N. Y.' pt. ii, p. 6; 1882. 

 Whitfield, Ann. N. Y. Acad. Sci. vol. ii, p. 217; 1885. Hall, Pal. N. Y. vol. v, 

 pt. 1, Lamellibr. ii, p. xxvii; 1887. Fischer, 'Man. de Conchyl.' p. 984; 1888. 

 (Ehlert, Bull. Soc. geol. France, ser. 3, vol. xvi, p. 653. 



1895. Ctenodonta, pars, Beushausen, Abhandl. Konigl. Preuss. Geol. Landesanst. 

 ser. 2, pt. xvii, p. 65. 



Observations. — The generic diagnosis has been given above, and 

 to it I have nothing to add. Palceoneilo differs from Nucula and 

 Nuculana in possessing no internal cartilage-pit, situated beneath, 

 the umbo, and between the anterior and posterior lines of teeth. 

 From Nucidites it also differs by having the row of hinge-teeth 



