LaMELLIBRANCHIATA. | UPPER PALZOZOIC MOLLUSCA. 503 
Epmonpia sutcata (Phill. Sp.) 
Ref. and Syn.=Sanguinolaria sulcata Phill. Geol. York. t. 5. f. 5. = Sanguinolaria concentrica Gold. in De 
la Beche, Man. 
Desc.— Oblong, rather more than twice as long as wide, uniformly convex ; depth of both valves about two- 
thirds the width from the beak to opposite ventral edge; posterior slope convex, undefined ; posterior end sub- 
truncate, not oblique, rounded, slightly gaping ; anterior end short, rounded, no trace of depression from beak 
to ventral margin; a small ovate lunette beneath the beaks, which are of moderate size: surface with large 
wrinkles on the posterior slope about two in a quarter of an inch at one inch from the beak, each of which 
divides into a bundle of two or three sharp narrow sulci on the body and anterior end of the shell. Length 
two inches two lines, proportional width from beak to opposite margin +, width of posterior end “2, length 
of anterior end =, depth of both valves =. 
This species is almost always found with the two valves together. The large posterior wrinkles dividing 
each into a number of small ones, as they cross over the body of the shell, give a curious character to the 
surface ; but sometimes the original ridges remain so strong as nearly to obliterate the minor ones. IT have 
not seen the surface perfectly preserved, but the casts shew obscure, punctured lines radiating from the beak to 
the ventral margin. Numerous finely preserved Lowick specimens in the Cambridge collection shew the ante- 
rior and posterior large oval adductor impressions, connected by a perfectly entire and distinctly marked pallial 
sear, (so that Mr King must have been deceived in this respect,) also the small accessory impression over 
each adductor, and the small deep slit left by the ridge bounding the lunette in front of the beaks and behind 
the retractor which is so short as not to reach even the upper edge of the adductor; it forms the anterior 
boundary of the internal dilated cartilage-plate, the posterior portion of which is continuous with the slit left 
by the internal cardinal posterior cartilage ridge, which extends about two-thirds the length from the beaks 
to the anal angle, running a little within the simple, erect, dorsal margin. 
Distinguished from the Sanguinolites sulcatus Flem, sp. (= Allorisma suleata + A. regularis King sp.) by 
the greatest gibbosity being, where the hollow from the marginal sinus in the anterior ventral margin occurs 
in that species; also by the splitting up of the wrinkles on the sides and their greater strength on the 
posterior slope, the strong internal cardinal-ridge, the erect dorsal edges, want of the parallel strize on the 
diagonal convexity, &c. I have occasionally seen a rare variety almost as finely plicated as the S. plicatus, 
from which however the convexity and obscure definition of the posterior slope will help to distinguish it. 
Position and Locality —Extremely abundant in the dark carboniferous limestone of Lowick, Northumber- 
land ; also, though less abundant, in the impure carboniferous limestone of Kendal. 
EpMONDIA UNIONIFORMIS (Phill. Sp.) 
Ref. and Syn. = Isocardia unioniformis Phill. Geol. York. Vol. II. t. 5. f. 18, 
Dese.—Ovato-oblong, evenly gibbous ; beaks large, obliquely inclined to the anterior side, approximate ; 
anterior lunette very large, oval, deep; anterior side very short, rounded ; posterior end slightly narrowed, ob- 
tusely rounded ; ventral margin very slightly convex; hinge-line nearly as long as the shell; posterior slope 
convex from the middle of the sides, no diagonal ridge; substance of the shell very thick; surface concen- 
trically marked with coarse strie and small irregular plicze (about four to six in two lines near the margin) 
parallel with the edges. Casts shew an extremely thick cartilage ridge, running beneath the simple, erect, car- 
dinal margin, and dilating within the cavity of the beaks, also the anterior and posterior adductor impressions 
connected by the simple pallial scar. Length one inch nine lines ; in proportion thereto, greatest width (from 
beak to ventral margin) %, width of posterior end =, length of anterior end 44, length of anterior lunette 2 
32 
width thereof <=, depth of one valve (greatest a little in front of the middle) =, thickness of the shell nearly one 
and half lines. 
Although the great prominence of the beaks makes the anterior end considerably wider than the posterior, 
yet this latter, in perfect specimens, is not quite so narrow as in Prof. Phillips’s figure, nor do I find the plica- 
[rasc. u1.] 3T 
