bo 
Or 
bo 
BRITISH PALHOZOIC FOSSILS. | Bracuioropa. 
Lingua pavist (M°Coy). Pl. 1. L. fig. 7. 
Ref—Id. M°Coy, Ann. Nat. Hist. 2nd Series, Vol. VIII. p. 405. 
Sp. Ch.—Ovato-pentagonal, or broadly subtrigonal, depressed, slightly and broadly convex near the beak, 
and about half way to the margins, which become gradually compressed ; greatest width at about the 
middle of the length; front slightly narrowed, but very wide, subtruncate, and very slightly convex ; obtusely 
rounded at the lateral angles to the subparallel, slightly convex, sides ; posterior lateral margins rather long, 
forming an obtuse angle at the sides (usually nearly equalling half the length of the shell, nearly straight, and 
meeting at the beak at an angle of about 100° in the short valve, and 95° in the long valve); surface with nu- 
merous faint, concentric, rather wide, subangular undulations of growth, accompanied by irregular, concentric, 
imbricating laminze; strie ten in one line on the exterior of the shell ; no trace of longitudinal external striz, 
but on the internal cast a few faint, obsolete, flattened, fibrous radiations, observable with the lens. Length 
seven lines, proportional width 7, depth about ;;. 
This curiously wide, satchel-shaped Lingula is the species discovered by Mr Davis in such profusion in the 
Lingula slates, near Tremadoe, in company with the large, elongate, L. ovata (M*Coy), and I have great pleasure 
in dedicating the species to him; at the same time I must remark, that except for a slightly greater width, and 
perhaps less coarsely undulated surface, it seems scarcely to differ from the Z. /ata of Pander. As, however, this 
writer gives no description of his species, as his figure indicates at least the difference noticed, and as Mr Sowerby 
has unfortunately described a totally different Silurian species under the same name, I think (although this latter 
should not retain the name of Z. ata) that it is better to give a distinct name to our very abundant and 
distinctly-marked species. The British species most allied to this is the L. attenuata (Sow.), which however 
is easily distinguished by its much longer, trigonal, retrally-narrowed form, rising from the gradual passage 
ofthe sides into the posterior lateral margins (without angulation), the very prominent narrow gibbosity from 
the beaks, &e. The substance of the shell is very thin, and the traces I have seen, apparently of the mesial 
ridge, extend little more than one-third the length of the shell. 
Position and Locality.—Extremely abundant in the greenish Lingula slates of Penmorfa, Tremadoc, 
N. Wales; rare in the Bala schists E. of Nant y Groes, S. of Bala, N. Wales; rare in the Bala limestone of 
Coniston, Lancashire. 
Explanation of Figures—P\. 1. L. fig. 7. Natural size, from the slates South of Penmorfa ; fig. 7 a, 
section of both valves about the middle; fig. 7 4, portion of surface and decorticated specimen magnified. 
LINGULA GRANULATA (Phill.) 
Ref —Phil. Mem. Geol. Surv. Vol. Il. Pt. 1. t. 25. 
Sp. Ch.—Shell pentagonal ; sides parallel, rather abruptly rounded into the nearly straight or slightly 
undulated front, forming an obtuse angle with the remarkably straight posterior lateral margins, which unite at the 
beak in a well-defined apical angle of 120°: surface very regularly marked, with nearly equal concentric wrinkles, 
or prominent laminze of growth, minutely undulated in the middle (about twelve in two lines in the middle of 
the shell, at six lines from the beak, abruptly diminishing at about seven lines from the beak to about ten in 
one line); crossed, particularly about the middle of the shell, by longitudinal strize (seven in one line), forming 
an obtusely tubercular reticulation, visible to the naked eye. Length eleven lines, proportional width =, 
depth ;;,- 
The thick, black, regularly wrinkled shell of this species is very easily recognized, even in fragments. The 
obtuse tuberculation is distinctly visible to the naked eye in good lights, and completely distinguishes this 
species from the ZL. tenwigranulata (M°Coy), but on the other hand appearing identical with that of the 
L. cancellata (Kutorga) from the Pulkova limestone (see Verhandlungen der Russ. Kaiserl. Min. Gesellschaft 
zu St. Petersburg for 1845, t. 7. f.5), from which however its great width and straight front seem to distinguish 
it perfectly. 
Position and Locality—Common in the Bala limestone of Llandeilo, Caermarthenshire; Bala grits of 
Tre Gib, Llandeilo. 
