444 BRITISH PAL/EOZOIC FOSSILS. [Bracnropop,, 
CAMEROPHORIA ISORYNCHA (M/‘Coy). 
Ref. and Syn. = Atrypa id. M°Coy, Syn. Foss. Irel. t. 18. f 8. 
Dese.-—Globose, subcuboidal ; adult specimens slightly deeper than wide ; lateral margins nearly straight ; 
commissures very blunt, scarcely angulated in the adult, at the sides strongly toothed; front margin abruptly 
raised into a rotundato-quadrate sinus; a large, sharply defined, broad, ovate, concave space, sulcated like the 
rest, formed partly of the posterior lateral margins of each valve, extending from the beak rather more than half 
the length. Receiving valve flattened near the beak, and nearly straight from thence along the margins of the 
very wide concave sinus, which begins to be formed after four or five lines from the beak; front, after about 
eight or nine lines from the beak, abruptly arched upwards, nearly at right angles to the plane of the rostral 
portion, to form part of the front; beak thick, obtuse, scarcely incurved ; apical angle about 88°; posterior 
lateral margins abruptly deflected at right angles with the mesial portion ; about three strong, angular, straight 
ridges extend on each side from the beak to the front margin at base of sinus, very deeply and angularly indent- 
ing the edge ; six or seven smaller ones on the deflected flattened or concave portion, strongly arched at their 
extremities; three or five simple angular ridges in the mesial hollow, resembling those of the sides ; sides of the 
hollow steeply inclined, but each divided by one of the ridges, so that there is no remarkably wide smooth space 
between the sulcation of the middle and of the sides. Entering valve very much elevated ; beak large, obtuse ; 
posterior lateral margins on each side of the beak abruptly deflected at rather more than right angles, forming 
a strongly defined concave area on each side; whole surface for a length of ten lines from the beak evenly and 
slightly convex, the profile being very slightly arched from a straight line, and the mesial ridge being scarcely 
indicated even at the margin; beyond this length the front and side margins are abruptly arched over, forming 
a nearly yertical front, at much more than a right angle with the plane of the rostral portion, and meeting the 
reflected portion of the opposite valve almost without angulation ; four or six strong, simple, angular ridges very 
slightly raised with the front sinus, four or five strong similar ridges on each side, and several (about four or 
five) abruptly smaller ones in the concave, posterior, lateral space ; all the ribs of both valves continued sharp 
and distinct to the beak. Average width of adult specimens one inch, proportional length of the nearly straight 
85 
rostral portion of entering valve ;%, depth of deflected front of ditto =, greatest depth of entering valve = 
greatest depth of receiving valve (at one-third from the front margin) ;;,, length of flattened rostral portion of 
receiving valve 7,, width of sinus at base =, depth thereof 10, length of lateral concave space ,{,, width of middle 
in entering valve =, at middle in receiving valve j;;. 
The above description is from a fine Irish specimen from the original locality of Cookstown, ‘Tyrone, where 
it is common in the red arenaceous limestone, like that of Dumfries, underlying the main limestone of the 
country. The English specimens, although exactly identical, are not so perfect. The mesial septum in the 
entering valve is strong, and about half the length of the flattened rostral portion; the mesial septum in the 
receiving valve is nearly as long, and diverges to form a large wide chamber at the beak. 
Position and Locality.—V ery common in the brownish siliceous carboniferous rocks near Shap Toll-bar. 
CAMEROPHORIA LATICLIVA (JM°Coy). Pl. 3. D. fig. 20 and 21. 
Ref. and Syn.= Atrypa id. M°Coy, Carb. Foss. Irel. t. 22. f. 16. 
Desc.—Transversely rhomboidal, wide, very deeply trilobed, rounded; triangular sinus in the front margin 
often as high as the entering valve is long, and either forming a right angle with the lateral margins or inclined 
backwards at an angle sometimes of 115°; middle of the sinus very deeply and angularly indented by three 
large, acutely-angular ridges, which extend from within two or three lines of the beak; sides very small, anterior 
Jateral margins very deeply reflexo-dentate by the ends of about three, large, acutely-angular ridges, which 
extend from within two or three lines of the beak; posterior lateral margins nearly straight, converging to 
the small beak at an angle of about 110°, having a shallow, very wide wave towards the entering valve, and 
a slightly flattened, narrow, elliptical space on each side very imperfectly defined. Entering valve with a 
