394 BRITISH PALAZOZOIC FOSSILS. [ LAMELLIBRANCHIATA. 
(sometimes exceeding the length), proportional length of hinge-line %, width of posterior margin ;;, depth of 
both valves %, length of anterior end ;¥,; surface with a few small concentric wrinkles and lines of growth. 
The nearly rectangular truncation of the posterior end, the quadrate form, and subcentral beaks, easily 
distinguish this species from its allies. The shell figured by Phillips (Pal. Foss.) as the C. trapezium of Sowerby, 
does not belong to that species, but is a well-marked example of the present one; the length varies from a little 
more to a little less than the width In only one specimen have I seen traces of the transverse pitting of 
cartilage area. 
Position and Locality——Not uncommon in the sandstone of Marwood, near Barnstaple; and, in probably 
the prolongation of the same bed, at Baggy Point. 
DoLaBRA? DAMNONIENSIS (Sow. Sp.) 
Ref. and Syn. = Avicula Damnoniensis Sow. Geol. Trans. 2nd Series, Vol. V. t. 53. f. 22. and Phill. Pal. 
Foss. figs. 90, 91 and 92. 
Sp. Ch.—Obliquely elongate, ovate, or subtrigonal, slightly tortuous ; left valve with a much larger beak 
and more gibbous than the right; beaks near the anterior end, which is small and rounded, except at the 
extremity of the hinge-line, which is slightly acute; valves most gibbous along a slightly sigmoid ridge, from 
the beak to the respiratory angle; posterior slope flattened or slightly concave ; posterior end wide, obliquely 
subtruncate, nearly straight, forming an angle of about 105° with the hinge-line ; respiratory angle narrow, 
rounded ; ventral margin slightly convex; entire surface marked with coarse, close, subequal, thread-like strize, 
radiating from the beak (about eight in the space of two lines at middle of ventral margin). Length from anterior 
end to respiratory angle one inch seven lines, proportional length of hinge-line =, width from beak to opposite 
point of ventral margin at right angles to the hinge %, length of anterior end ;5, width of posterior end =, 
depth of left valve =, of right valve =. 
The slender posterior lateral tooth or cardinal ridge is very long in each valve, and runs nearly parallel 
with the diagonal ridge; there is also a short distinct anterior one curving towards the ventral margin, from 
immediately in front of the beaks. Although the typical varieties of this species depart considerably from those 
so-called Cuculleece in appearance, yet there seems no real generic distinction between them ; there is the same 
inequality of valves, the same straight hinge-line in front as well as behind the beaks, the same transverse 
pitting of the cartilage-area, and the same long, internal, straight, lateral ridges, or cardinal teeth in both; and 
it is certain at least that this species is not a true Avicula. By a careful management of the light I have 
distinctly seen the radiating strize over the whole of the posterior slope in one of the specimens from which Mr 
Sowerby described the species. 
Position and Locality—Common in the sandstone at Marwood, near Barnstaple. 
DoLABRA DEPRESSA (Phill. Sp.) 
Ref. and Syn.= Cucullwa depressa Phill. Pal. Foss. f. 71. 
Sp. Ch.—Longitudinally oblong ; beaks obtuse near the anterior end, which is short and rounded; valves 
moderately convex, most tumid near the beaks and anterior end ; hinge-line long; ventral margin only slightly 
convex, subparallel with the hinge-line; posterior end obliquely truncate, straight, forming an angle with the 
hinge-line of only about 115°; posterior slope flattened ; diagonal ridge only obscurely marked; surface with a 
few, irregular, small, concentric wrinkles and lines of growth. Length from anterior end to respiratory angle 
two inches five lines, proportional width from beak to ventral margin at right angles to the hinge =, length of 
anterior end about }%, length of hinge-line about =, length of posterior margin depth of right valve =, 
depth of left valve % 
100 * 
65 
T00> 
Though Prof. Phillips describes the length and width to be nearly equal, yet his figure shews about the 
same proportions I have indicated above, and which I found to obtain in a number of specimens which I collected 
at Baggy Point, in the precise strike of the Marwood bed in which Phillips procured his species, but where I 
