LaMELLIBRANCHIATA. | DEVONIAN MOLLUSCA. 397 
Genus. NUCULA. See page 285. 
Nucuta Kracuta (Rémer). 
Ref—Harzgebirge, t. 6. f. 10. 
Sp. Ch.—Obliquely arched, subovate ; beaks very high, obtuse, prominent close to the anterior end, towards 
which the hinge-line slopes rapidly, the lower portion semielliptically rounded ; ventral margin very convex, the 
posterior end seeming slightly recurved ; posterior end narrowed from the rapid sloping of the hinge-line from 
the beak, obliquely rounded; valves evenly tumid, about five strong teeth in front of the beak, and about eleven 
strong ones behind it (? surface with very sharp, fine, concentric strie). Length from anterior to posterior end 
five lines, proportional length of anterior end ;3, width from beak to opposite point of ventral margin ;;;, length 
of posterior hinge-line from beak 7, width of posterior end ,*,, depth of one valve about =. 
The very high, tumid, nearly terminal beaks, and the narrow subrecuryed appearance of the posterior end, 
from the great convexity of the ventral margin, easily separate this species from any other in the Paleozoic rocks. 
Position and Locality —1 have collected several specimens of this species in the Devonian schists of 
Linton, North Devon. 
NUCULA PULLASTRIFORMIS (J/°Coy). 
Ref. and Syn. = Pullastra antiqua Sow. Geol. Trans. 2nd Series, Vol. V. t. 53. f. 28. 
Sp. Ch.—Ovate, moderately elongate, compressed ; valves gently and evenly convex; beaks small, obtuse ; 
anterior lunette narrow, elliptical, deep; anterior end broad, semielliptically rounded; ventral margin gently 
convex; posterior end gradually narrowed, by the slight convergence of the cardinal and ventral margins ; 
posterior slope extremely narrow; posterior margin elliptically subtruncate, rounded ; surface covered with very 
regular, narrow, elevated, delicate, concentric ridges, separated by flattened spaces, about double their width 
(eight ridges in two lines, about the middle of the shell). Length nine and half lines, proportional width from 
beak to opposite ventral margin ;;, length of anterior end ;;;, length of hinge-line from behind beak ;%, width 
of posterior end about ;5,, depth of one valve about ie 
I see traces of the hinge-teeth of Nucula along both the posterior hinge-line and the anterior lunette of 
this beautiful shell, which certainly also wants the teeth of Pudlastra, in which genus Mr Sowerby has placed it 
with the name Pullastra antiqua. In placing it in the genus Nuecula I should have adopted his specific name, 
but it is already preoccupied by a species figured and described by Hisinger ; I have therefore to propose a new 
specific name, and adopt one indicating the resemblance in form, anterior lunette, and sculpturing, which deceived 
Mr Sowerby. 
Position and Locality—Rare in the sandstone of Marwood. 
SANGUINOLARIA? ELLIPTICA (Phill.) 
Ref —Pal. Foss. f. 53. 
Sp. Ch.—Elliptical, beaks obtuse, a little nearer the anterior than the posterior end ; length varying greatly, 
apparently from pressure, becoming sometimes nearly orbicular ; anterior end obtusely rounded ; posterior end 
obtusely rounded, slightly narrowed, obliquely subtruncate ; valves moderately and evenly convex, becoming 
gradually compressed towards the margin; texture very thin, apparently corneous; surface with fine, con- 
centric, close, imbricating lines, and minute, irregular, concentric wrinkles, reticulated by very minute, irregular, 
anastomosing plicee under the lens. Average length five and half lines, proportional width from beak varying 
from = to &. 
There is no trace of hinge-teeth, nor sinuate pallial scar, in any of the very numerous specimens which I 
have collected with their valves expanded, but still connected; nor can I see any reasons for placing the fossil 
in the genus Sanguinolaria. The peculiar texture of the valves inclines one to suspect that they might be 
bivalve crustaceans allied to the large Cyclas-shaped living Jsaura. 
Position and Locality—Extremely abundant in the upper yellowish part of the slate at Lanlake, Laun- 
ceston; more rare in a fine black layer of the same rock at S. Petherwin. 
