222 
.4. E. Yerrill — Xorth American Cephalopoda. 
of tlie suckers, some of them ( e , g) slightly exceeding the largest of 
those described ou p. 201, but showing no distinct variation; others 
(^) are completely intermediate between the two principal forms, 
having very oblique rims, with a small aperture, but distinctly 
denticulate all around, the denticles on the inner margin being 
distinctly smaller than on the outer. 
The following table of measurements will supplement those on 
page 201. 
Measurements of sucker-rims from short arms (millimeters). 
e. f. 
g. h. 
t. 
j- 
Diameter, at base 
21 19 
205 16 
14-5 
11 
Diameter of aperture 
17 16 
16 5 9 5 
9 
4’5 
Height or breadth of ring, at back, 
8 7’5 
7'5 95 
7 
6 
“ “ front side, 
3 3 
3 3 
2 
1 5 
Number of distinct denticles 
50 48 
49 | 34 
14 
7 
Sthenoteuthis, gen. nov. 
(Type Architeuthis megaptera Yerrill.) 
This group is instituted to include certain species of squids, remark- 
aide for the large size and high development of their organs of loco- 
motion. especially of the caudal fin and siphon, and for the presence 
of a broad, thin web along the lower side of the lateral arms, outside 
the suckers. 
The tentacular-arms are, like those of Architeuthis , very long, 
slender, and provided, at the base of the club, with smooth-rimmed 
suckers alternating with rounded tubercles, for the mutual adhesion 
of the two arms; the central part of the club is, as in Architeuthis , 
provided with two central rows of large serrated suckers, and a row 
of smaller marginal ones, on each side, of different form, alternating 
with them. The lateral arms have a well-developed median crest, 
(most developed on the third pair) along the outer side ; on the lower 
inner angle there is a thin, membranous web, often more than twice 
as wide as the arm, along the whole length, much more highly de- 
veloped than in typical Ommastrephes , in which a narrow marginal 
membrane occurs. On the ventral arms the inner face is broader than 
ou the others, and the two rows of suckers are wider apart. The 
suckers ou all the sessile arms are strongly denticulated on the outer 
side of the rim, with smaller or obsolete teeth on the inner side. 
Caudal tin very large, rhomboidal. Internal bone or pen similar 
to that of Ommastrephes. 
Odontophore with seven rows of teeth, median tooth with three 
