312 
A. E. Verrill — North American Cephalopods. 
curved, with a triangular notch at its base, followed by a prominent 
triangular tooth on the alar edge, beyond which the edge is nearly 
straight, but recedes somewhat. Lower mandible with a sharply 
incurved point and sinuous cutting edges, which have a slight tooth 
below the middle and only a slight rounded notch at base, which 
passes gradually into the very oblique and receding alar edge. The 
bilobed palate is covered with a chitinous membrane which bears 
transparent, small, sharp, recurved denticles. 
Odontophore with pale amber-colored teeth, and thin transparent 
borders. The median teeth (PI. XXXIV, fig. 3; PI. XXXVII, fig. 
6, a ; PI. XXXIX, fig. 4) are broad with a long acute median denticle, 
and a shorter curved and less acute lateral one, on each side ; the 
inner lateral teeth are short, strongly incurved, with a longer acute 
central denticle and a smaller outer one, and with the inner angle of 
the base slightly prominent ; the next to the outer lateral teeth 
(fig. 6, c) are much longer, broad, tapered, curved, acute; the outer 
teeth (fig. 6, d) are longer, more slender, more curved, triquetral, and 
very acute with a large basal lobe. A row of thin, distinct, roundish 
scales (fig.6, e) forms a border, outside the teeth. 
The pen is thin, translucent, pale yellowish, in fresh specimens, but 
brownish or amber-color in alcoholic specimens. It has a short, nar- 
row, anterior shaft and a long, very thin, lanceolate blade, which is 
concave beneath, especially posteriorly, for the edges curve down- 
ward, but are not involute ; the posterior tip is acute, slightly thick- 
ened and curved downward, so that the posterior end is shaped some- 
thing like the forward part of a shallow canoe. In the male the pen 
is relatively longer and the blade narrower than in the female. The 
extreme anterior end is thin and flexible, and rather abruptly pointed, 
being shaped like a pen ; the shaft is rather stiff, with a strong, regu- 
larly rounded keel, convex above and concave beneath ; outside of 
the keel the marginal portion curves outward and then upward, ^o 
that its convex surface is below, and the edge slightly turns Tip. 
The shaft, with its central keel and marginal ridges, extends to the 
posterior tip of the pen, decreasing regularly in width beyond the 
commencement of the blade. The blade is at first very narrow, and 
gradually increases in width ; it is marked by numerous slightly 
thickened ridges, which diverge from the central line as they extend 
backward ; the edges are very thin. 
In the larger males the proportion of the greatest breadth of the 
blade to the total length of the pen varies from 1 : 7*50 to 1 : 9‘36. 
In the females it varies from 1 : 5 ’60 to 1 : 6'10. 
