114 TRANSACTIONS OF THE [MaR. 17, 
is markedly concave, so that the pedicel groove,as we look 
into the interior of the valve, is seen to start from the bottom 
without any shoulder such as is seen in other species. The 
scars of the central‘and lateral muscles are distinct, and extend 
beyond the middle of the valve. The inner surface of the edge 
of this valve has on each side of the area a narrow triangular 
groove, which appears to be a sliding articulation for the dorsal 
valve; further forward, on the inner edge of the valve, is another 
but narrower linear groove apparently for a similar use. 
Interior of the dorsal valve. This exhibits a broad median 
ridge extending more than half the length of the valve; the 
ridge is divided longitudinally in the posterior half by a shallow 
furrow. Imprints of the cardinal and lateral muscles are visi- 
ble at the back of the valve; the edges of the valve are some- 
what flattened on the inside. 
Varieties. Beside the type figured in the Transactions of the 
Royal Society of Canada, there is an obtuse form in which the 
ventral valve has a rounded posterior end, and the sides are 
more fully rounded (see P1.II., fig. 6); in this the pedicle groove 
is one-fifth of the whole length of the valve. There is also an 
acute form in which the sides are nearly straight for two-thirds 
of the length of the valve, and the deltidial area is acuminate ; 
in this the pedicle groove is two-sevenths of the length of the 
valve. 
Horizon and locality. This species has been found to have a 
wider range than it was at first known to have. Besides the 
original location in Assise 1, where the type and the two varie- 
ties occur, the acute variety has been found in Assise 3. 
In its hinge area, and to some extent in the arrangement of 
the muscle scars, this species resembles Leptobolus grandis of 
the h orizon 3 e (Division 3, Band e), of the St. John group; it 
also compares with some species of Obolus, as O (Botsfordia) 
pulchra. A general resemblance exists between L. Martinensis 
and LZ. Ella of the ‘‘ Middle” Cambrian of Nevada, but our spe- 
cies is larger, less orbicular, more rugose on the surface of the 
valve, and with different sculpturing of the interior of the valve. 
LINGULELLA cf. GRANVILLENSIS, Walcott. Pl. II., figs. 7 a and b. 
Fauna of “ Upper Taconic,’’ Am. Jour. Sci., vol. xxxiv., Sept. 
1887. 
Ovate, ventral valve rather flat, acuminate at the apex, sides 
curved gradually for two-thirds of the length of the valve, thence 
more rapidly to the front of the valve. Deltidial area small, 
pedicle groove one-eighth of the length of the valve. 
