[ 217 ] CEPHALOPODS OF NORTHEASTERN COAST OF AMERICA. 
tact beneath; eye-lids thin, entire. The body is long - , somewhat fusi¬ 
form, slightly smaller in advance of the middle. The tissues are exceed¬ 
ingly thin, delicate, pale, and translucent, so that the pen and other 
organs can be seen through the mantle. Anteriorly the edge of the 
mantle is directly attached to the head, medially, by a muscular com¬ 
missure, and there is no free edge (such as D’Orbigny figures in Taonius 
pavo) at the narrow middle portion of this band. This commissure is 
broader within the mantle, and there is another large, oblique, muscular 
commissure, extending forward to the edge of the mantle, on each side, 
extensively uniting the inner surface of the mantle to the sides of the 
siphon. These commissures leave only a rather narrow opening to the 
gill-cavity, on each side, and one small ventral one, and the interior 
ventral cavity is partitioned off from the lateral ones. 
The siphon is large, projecting forward between the lower sides of the 
large eyes; it has no valve in the ordinary place, but toward the base, 
on the dorsal side, there are two erect, rounded, ear-like flaps, each ac¬ 
companied by a prominent papilla (i 1 ), and farther forward a raised, me¬ 
dian, transverse fold, and a central papilla (i). (Plate XLV, fig. 2d.) 
The caudal fin is comparatively small, narrow-ovate, tapering to a 
short, blunt posterior end, and with the anterior lobes narrowed and 
scarcely projecting beyond the insertions. 
Arms rounded, rather slender, tapering to slender tips; those of the 
third pair are much the longest, and like the second pair, bear along 
the distal half suckers much larger than the proximal ones; tips short, 
with few small suckers. The dorsal and ventral arms are about equal, 
and not much more than half as long as the third pair; they bear smaller 
suckers, in two rows, regularly decreasing distally. The second pair is 
intermediate in length between the first and third pairs, with two rows 
of larger suckers on the outer half, suddenly decreasing distally, with 
minute ones close to the tip. The large suckers (fig. 2 &, 2c) on the second 
and third pairs of arms are much larger than the others, but similar in 
form, deep cup-shaped, convex in the middle, obliquely attached, with 
a smooth horny rim, except on the distal ones, which have blunt denti¬ 
cles externally. There are about sixteen of these suckers on each of 
the lateral arms, but eight or ten are decidedly larger than the rest. 
The large suckers commence nearly at the middle of the arms and ex¬ 
tend to very near the tips. The third pair of arms have a thin median 
carina on the outer side, along the distal third. All the arms have a 
wide marginal or protective membrane along the inner edges, outside 
the suckers; these membranes are strengthened by transverse thick¬ 
ened, muscular processes, opposite each sucker; between these the mem¬ 
brane recedes so that the edge is scolloped. The ventral arms have 
also a membrane along the outer, ventral angle. I am unable to detect 
any positive signs of liectocotylization, either in the dorsal or ventral 
arms. Perhaps the presence of the very large suckers on the lateral 
arms may be a sexual character, but if so, they are symmetrical on the 
two sides. 
