22 
THE GEOLOGIST. 
XVIII. — SpiRrFERiNA iNscuLPTA. Pliillips. PI. xii., fig. 35. 
Spin/era msculpta, Phillips, Geol. of Yorksliirc, vol. ii., p. 210, pi. ix., figs. 
2, 3, 1836 ; aud Dav. Mon. Carb., p. 42, plate vii., figs. 48-55. 
In shape it is more or less semi-circular, and about one-third wider than 
long ; the lunge-area is straiglit and as wide as the greatest width of the shell. 
The area large, triangular, and but slightly curved ; beak small, and not much 
produced. Both valves are about equally convex ; the ventral one is 
ornamented with five (rarely seven) large bold angular ribs, of which the 
central one exceeds the others somewhat in proportion, and corresponds with a 
deep angular sinus in the opposite valve. All the ribs are sculptured, or 
closely mtcrsected with small concentric laminae, which give to the perfect 
shell a very elegant appearance. This is a rare Scottish shell ; it occurs at 
Gare, in Lanarkshire, at two hnndred and thirty-nine fathoms below the " Ell 
coal." 
PaMILY RUYNCnONELLID^. 
Of this family the genera Rlujnchonella and Camarophoria alone have been 
hitherto discovered in the Scottish carboniferous strata. Of the first we know 
but two species, and one only of the second ; whUe in England eight of Rhyn- 
chonella and three of Camarophoria have been found. 
Genus RnYNcnoNELLA. Pischer. 1809. 
The shells composing this genus vary much in their external shape and 
appearance, some being transverse, others rounded or angular, smooth, variously 
riboed, or striated. The valves are generally convex, with or without a mesial 
elevation or sinus ; the beak is acute, prominent, or so greatly incurved as to 
touch and even to overlie the umbone of the opposite valve ; the foramen is 
variable in its dimensions and shape, being placed under the extremity of the 
beak, and entirely or partially surrounded by a deltidium. The shell-structure 
is fibrous aud not perforated ; and the valves articulate by the means of two 
teeth in the ventral, and corresponding sockets in the dorsal valves. The 
is perhaps more correct to separate them into two. The Carboniferous, or Hibernian lime- 
stone is fifty feet tliick at Dnunifuiii in Tyrone, it is aljout fifteen hundred feet thick at Black 
Head in Clai'e, and occupies above twenty thousand square miles in Ireland. Tliis greatly 
predominates ; the coal-measures are two thousand feet thick, or more. The Old Reel sand- 
stone, at Kildi'ess in Tyrone, and the Old Red Sandstone of Herefordshire are two very dif- 
ferent tilings. The first belongs to the Carboniferous system ; the latter is a subdivision of 
the Silurian rocks." 
My mistake was not therefore in in the order of superj^iosition of the different strata, 
which Mr. Kelly ailmits to be con'ect ; but in having endeavoured to reconcile the succession 
of the Carboniferous strata in Scotland with that of Ireland by applying Mj'. Page's general 
denomination of "Lower Coal-measures" to that group which emifraces all the alternations of 
strata which Ue between the Old Red Sandstone and the mountain- or Carboniferous- 
limestone. The term, however, would not apply to Ireland, since in the sister island no 
lower coal-measures imderlie the moimtain-Umestone, as we find to be the case in Scotland, 
and where Mr. Kelly suggests that the limestone may be moved up a stage, with coal- 
measures below it. it must appear evident to all that the term Old Red Sandstone cannot be 
retained for a Silurian, Devonian, and Cai'boniferous rock, and tliis is the reason why I was, 
and still am, so averse to api)lying the term, or forming a subdivision by that name for those 
Irish red and yellow sandstones full of carboniferous fossils ; for if the C.alciferous- and 
mountain-hmestone might, according to Mr. Kelly's own statement, be united into a single 
division on account of the similarity of their fossils, as a paleontologist, I should add that 
the same reasoning might equally well apply to the red sandstone of Kildress, for there also 
we find exactly the same fossils as those wljich occur in the calciferous and carboniferous- 
limestone, l' should therefore suggest that geologists should drop the tenn " old," and 
in their subdivisions of the Carboniferous group say, 1, Lower carboniferous red and yel- 
low sandstone ; 2, calciferous slate ; 3, carboniferous-limestone ; and, 4th, coal-measures, by 
which means the vexed question relative to the Old Red Sandstone would not be interfered 
with as far as the Carboniferous system is concerned. It is .also well known that Mr. KeUy is 
of opinion that no Devoni.an rocks occur in Ireland; while Sir R. Murchison beUeves that 
there exists there also a series of many thousand feet of shales and grits above the highest 
Tipper Silurian which represents precisely in time the mass of the Devonian rocks ; this, 
however, has nothing to do with the red and yellow sandstone of Kildress which un- 
doubtedly forms part of the Carboniferous system. 
