A. E. Yerrill — Forth American Cephalopoda. 
207 
inches of the anterior end, from close to the extreme tip backward ; 
the second section includes about nine inches, belonging to the ante- 
rior portion, and extends to about twenty-five inches from the ante- 
rior end, but lacks the extreme lateral margins, outside the costa? 
(Plate XV, fig. 3) ; the third section cousists of about 7*5 inches 
belonging to the middle region, but does not include the whole width 
on either side of the midrib; the fourth section is about 10 inches in 
length, and comes from close to the posterior end, apparently repre- 
senting nearly the whole width, on both sides. 
From these fragments we can restore, pretty accurately, the first 
twenty-five inches, and the last twelve inches or more, though the 
precise form of the indefinite posterior margin must remain doubtful. 
The extreme anterior tip is broken off*, but it was evidently pointed 
and pen-shaped, as in Loligo. At the mutilated end the breadth is 
now about a third of an inch. From this point the lateral edges 
diverge rapidly with a slightly concave outline, for about 1"25 inches, 
where the breadth becomes 1-20 inches; beyond this the margins are 
nearly straight and diverge gradually to the end of the first section, 
at eleven inches from the tip. At this place the breadth is 3*10 
inches, the marginal portions, outside of the lateral cost*, beiuo- 
about AO of an inch, and the midrib about “25 of an inch broad. 
Beyond this point a section about 4-75 inches long is entirely want- 
ing, and the succeeding section lacks the marginal portions, the late- 
ral cost* forming the margins on both sides. At 19-50 inches from 
the tip, the breadth, between the lateral cost*, is 3’75 inches; at 25 
inches it is 5 inches broad. Whether the marginal portions origin- 
ally extended to this point with a breadth as great as they have at 
11 inches is uncertain, for their breadth decreases backward to that 
point from a point about 4 inches from the tip, where their breadth 
is 60 of an inch. The midrib is strongly marked, being raised into 
a semi-cylindrical form, and of somewhat thicker material than the 
lateral portions; its breadth and height steadily increases throughout 
both these sections and the following one, until it becomes nearly 
half an inch broad, but in the section from near the posterior end it 
is low and narrow and decreases rapidly toward the end. The 
lateral cost* are well-marked, considerably elevated, and well 
rounded ; they run, at first, close to and nearly parallel with the mid- 
rib, but after the first three inches they diverge <piite regularly to the 
point, at 25 inches from the end, beyond which we cannot trace them 
until they reappear in the first part of the posterior section, where 
they are quite small and soon fade out entirely, at some distance from 
