280 BRITISH PALAOZOIC FOSSILS. [ LAMELLIBRANCHIATA, 
Genus. GRAMMYSIA (Vern.) emend. 
Gen. Char.—Equivalve, inequilateral, shell thick, oblong; anterior side short, contracted by a deep oval 
lunette beneath the beak ; posterior end elliptically rounded; hinge-line straight; two large, strong, adductor 
impressions in each valve, the anterior rounded, posterior pear-shaped ; pallial scar entire ; cartilage external, 
short, in the anterior part of a deep longitudinal depression, formed by the inflexion of the hinge-margins ; an 
oblique furrow extends from the beak to about the middle of the ventral margin, of the right valve, usually one 
or two additional ones in the left valve. 
By the short external cartilage, and long, dorsal, concave lunette formed by the inflexion of the dorsal 
margin of the valves, &c., this genus agrees with Sanguinolites (M°Coy), and differs only in the few, strong, 
oblique, girth-like furrows which divide the valves from the beak to the ventral margin, being therefore probably 
a subgenus thereof. 
GRAMMYSIA CINGULATA (fis. Sp.) Var. a. 
Ref. and Syn.= Nucula cingulata Hisinger, t. 39. f. 1.=Orthonota Id. Mem. Geol. Surv. t. 17. f. 3. Var. 8. 
triangulata Salt. Mem. Geol. Surv. Vol. IT. Pt 1. t. 17. f.1. Var. y. obliqua M°Coy, Mem. Geol. 
Surv. t. 17. f. 2. 
Sp. Ch.—Oblong, subcompressed, valves gently convex ; beaks obtuse, moderate, close to the anterior end, 
which is short, oblique, rounded; anterior lunette ovate, deep ; posterior lunette large, concave, as long as the 
hinge ; posterior end not narrowed, obliquely rounded ; in the right valve one strong deep sulcus extends from 
the beak to a little in front or behind the middle of the ventral margin, often with a second sulcus in front of it, 
distinct and defining a narrow ridge between them near the beak, becoming obsolete towards the margin, or 
both nearly obsolete, leaving the ridge distinct; corresponding part of the left valve with three sulci, defining 
two narrow, oblique ridges; surface with small, unequal, irregular, concentric wrinkles and lines. Length one 
inch six and half lines, proportional width ;\;, length of anterior end ;;, depth of both valves =. 
‘Vhe above description is from a specimen strongly resembling Hisinger’s one, and a slight variety; the 
species is, however, very variable, and Mr Salter has given a particular name to the next variety. 
Var. B. (triangulata) Salt. sp. Pl. 1. K. f. 28. 
Ovate, or subtriangular from the narrowing of the posterior end; beaks large, from one-fifth to one-fourth 
from the anterior end, which is narrowed and strongly wrinkled concentrically, rest of surface with finer wrinkles 
and striz of growth; in the left valve two approximate rounded ridges run from the beak to a little behind the 
middle of the ventral margin, defined either by three sulci, or only the one between them; in the corresponding 
part of the right valve there is one strong sulcus, sometimes with a second in front of it defining a ridge. 
Length one inch nine lines, proportional width ,%;, width at posterior end =, length of anterior end ;;,. 
I have given a figure and description of a strongly marked example of this form which is mainly distin- 
guished from Var. a. by its narrow posterior end, and slightly longer anterior end ; the wrinkles on the anterior 
end are often absent, the form and other characters remaining the same. The obliquity of the oblique sulci 
also varies considerably. 
Var. y. (obliqua) M°Coy. 
Obliquely oval, anterior and posterior ends rounded; each valve with one very oblique, wide, deep sulcus, 
bounded by two obscure ridges running from the beak to a little in front of the obtusely rounded respiratory 
angle ; surface with small irregular plicze and striz of growth, largest about the middle. Length one inch three 
lines, proportional width *4, width at posterior end =, length of anterior end ;;, depth of both valves 5. 
The short elliptical form, and very oblique or backward running sulci, distinguish this rare species or 
variety perfectly. The aboye quoted figure of the Geol. Survey is very good. 
