516 BRITISH PALAZOZOIC FOSSILS, [ LAMELLIBRANCHIATA. 
Length two inches three lines, proportional width %°, depth of both valves %, length of anterior end 
about 34, width of posterior end =. 
Position and Locality —V ery common in the coal-shale of Bradford, Yorkshire. 
CARBONICOLA TURGIDA (Brown Sp.) 
Ref. and Syn. = Pachyodon turgidus Brown, Ann. Nat. Hist. Vol. XII. t. 16. f. 13, 14. 
Dese.—Subquadrate, obtusely oblong, very gibbous; beaks large, obtuse, tumid, approximate, close to the 
anterior end; cordate depression in front of them broad, deep, with obtusely rounded edges; anterior side 
projecting very little beyond the beaks, broad, and but little convex or obscurely subtruncate at the margin ; 
posterior end short, broad, obtuse, obliquely subtruncate, the angles broadly rounded ; ventral margin nearly 
straight ; hinge-line only slightly converging to the posterior end; valves very tumid, gradually compressed 
towards the ventral margin, abruptly rounded towards the anterior margin; posterior slope flattened, extending 
from the hinge-line to the respiratory angle, the diagonal ridge very obtusely rounded ; surface with irregular 
strie and minute concentric plicee of growth, and a few short, thick, extremely irregular, oblique wrinkles 
(apparently due to a thick periostraca). Length of small specimen one inch, proportional greatest width from 
52 
beak to opposite ventral margin ;, width of posterior end about ;;,, length of anterior end about 2, length of 
hinge-line from beak about =, from beak to respiratory angle ;;,, depth of both valves %. 
This species is easily distinguished from all others by its short quadrate form, and evenly-gibbous, very 
tumid valves. 
Position and Locality.—Rare in the coal-shale of Bradford. 
. (Family uncertain). 
Genus. CONOCARDIUM (Bronn). 
Syn. = Pleurorhynchus (Phill.) 
Gen. Char.—Kquivalve, very inequilateral, hemifusiform; beaks prominent, incurved, close to the anterior 
end, which is broad, flattened, more or less truncate nearly at right angles to the straight hinge-line, which is 
prolonged as an abruptly-contracted, slender, tubular wing from the dorsal part of the anterior face ; body of 
the shell diminishing conoidally from the edge of the anterior face towards the posterior end, which is attenuated, 
rounded, and widely gaping ; substance of the shell very thick, of a minute quadrangular cellular tissue, with 
strong internal ribs radiating from the beak, and often smaller external ones, strongest on the anterior face. 
In several species there is a keel-like expansion projecting forwards at right angles to the anterior face 
from its margin. Bronn and most paleontologists have considered this genus to be most closely allied to 
Cardium, from which the tubular anterior wing separates it: Conrad insists on the remarkable resemblance to 
Pterinea, from which it is however separated by being equivalve ; in Professor Phillips’s opinion Tridacna is 
the nearest analogue, and this is also the last opinion of M. de Koninck: but I have been unable to ascertain 
with certainty whether the adductor impressions are distinctly separated, or are united in the middle, as this 
affinity would require. I might mention however that four internal casts in the collection from Lowick all have 
the stone strongly adhering at the deepest part of each valve in the middle towards the beaks, making the latter 
very probable. Professor Agassiz refers the genus to the Brachiopoda, without stating fully the reasons for a 
rapprochement, which seems at variance with all its characters. The cellular tissue of the thick shell reminds us 
of certain Rudistes, but the analogy holds good in no other respects. 
CONOCARDIUM ALIFORME (Sow. Sp.) 
Ref. and Syn. = Cardium aliforme Sow. Min. Con. t. 552. f. 2.= Pleurorhynchus minaz Phill. Geol. York. 
Viol. UH. yon tire 
Desc.—Subtrigonal or deltoidal; hinge-line straight ; beaks narrow, obtuse, prominent, much incurved at 
the anterior end; anterior end subtruncate, forming a cordate space, bounded by a distinct angulation, near 
