184 
recurved, on itself ; the deltoid fissure is large ; and the extremities of the 
ears are rounded. The dorsal ridge is broad and prominent, and is divided 
centrally by a longitudinal, shallow, but distinct furrow, the existence of 
which has no influence on the regular form of the ventral furrow. On each 
side of the dorsal ridge are four folds corresponding with, and analogous to, 
those of the ventral valve. The surface is ornamented by a number of 
irregular concentric rings of growth, most apparent near the margins of the 
shell. The internal casts prove that the shell was very thick near the cardinal 
process, as will be seen from PI. XIII, Pigs. 1 and la. Their structure is 
like that of the other Spirifers belonging to the same section. 
Dimensions. — One very nearly perfect specimen measures fifty-five 
millimetres long, seventy-four broad, and thirty-two thick. 
Delations and Differences . — This Spirifer is easily distinguished 
from the preceding species by the absence of the mesial fold in the ventral 
furrow. Its much more transverse form, added to the size and greater depth 
of S. Darwinii, prevent confusion with this last. S. neglectus, J. Hall,^ 
is decidedly the species to which it bears the greatest resemblance ; but the 
different proportions, the absence of the mesial fold in the ventral furrow of 
S. neglectus, and the much greater number of its lateral folds, suffice to 
distinguish it. Mr. H. Etheridge seems to have confounded this species with 
S. undiferus, E. Eoemer, to which it, nevertheless, bears only a remote 
resemblance. 
Horizon and Localities. — Two specimens with their shells preserved 
were found, one in the railway- eutting between Maitland and Stony Creek, 
and the other about thirty-four miles from Newcastle. Many casts have 
come from Muree Quarry, Eaymond Terrace, and from the aforementioned 
localities. Mr. E. Etheridge found this species at Gympie, Queensland, and 
he is of opinion that it is Devonian, which seems to me highly problematical. 
Spieifee Claekei, L. O. de Koninch? 
PL XIII, Pig. 2. 
This is a transverse, subelliptical shell, having its greatest diameter at 
the hinge-line. The ventral valve has a broad, shallow furrow, at the bottom 
of which are sometimes visible two or three rudimentary folds ; on each side 
1 Kept. Geol. Survey Iowa, I, Pt. 2, p. 643, PI. 20, Fig. 5 . 
^ [Compare E. Etheridge, Junr., Geol. and Pal. Q’lancl, 1892, p. 229, t. 10, f. 16. — W.S.D.] 
