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, aciite; 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, so 

 that its convex surface is below, and the edge slightly turns up. 

 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 

 o-radually 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, 



