AND ACCOUNT OF A NEW SPECIES OF SEPIOLA. 79 
with connecting folds, they are probably developed here chiefly to sheath the tentacula. 
The Octopods which have no tentacula have membranes extended between the bases of 
all their arms to serve as organs of progressive motion, because they have no other fins. 
The form of the two circular lips around the mouth, the structure of the horny man- 
dibles, and the arrangement of the muscles which move them, agree with those of Lo- 
ligo. Theskin of the head passes transparent over the pupil, presenting only a slight 
looseness above the eye, which by folding produces the appearance of an upper longi- 
tudinal eye-lid. The eyes are very large and prominent, and with a remarkable sub- 
dorsal aspect. I have often found this animal broader across the eyes than at any other 
part of the body. The back part of the head is continuous with the dorsal margin of 
the mantle, where the dorsal /amina commences, for about a line in breadth, giving con- 
siderable support to both parts of the body. The free margin of the mantle in all the 
specimens I have seen, has a white band passing round the orifice of the sac. It is en- 
tirely destitute of the usual spotted markings of the surface, and it appears as if the 
spotted skin were forcibly retracted to the extent of half a line around the margin, 
and thus drew out the white lining membrane of the interior of the sac. The body of 
this animal.is scarcely ventricose, being generally as wide at the upper margin of the 
sac as at its middle, and it is suddenly rounded and broad at the base. It is supported 
feebly along the middle of the back by a thin, short, tapering dorsal lamina, lodged, 
as usual, loosely in a capsule, without receiving any muscular insertions. It is broadest 
at the upper end, where it measures about half a line in breadth, and tapers regularly 
to a point as fine as a hair, extending only about a third of the length of the mantle!. 
On removing the skin from the place occupied by this most minute dorsal lamina, a 
dark line is seen extending along its course in the back. The existence of this short 
dorsal lamina in Sepiola is the only anatomical fact regarding this animal recorded by 
Cuvier, Lamarck, and other naturalists, and it forms a peculiarity by which it differs 
from all the known Loligines with which this animal has been generally associated. 
The two dorsal fins? are of great size and strength, though attached but loosely to the 
back of the mantle near the median plane. They are attached obliquely to the trunk, 
so as to strike the water most readily backwards and downwards during the act of 
swimming ; they have a deep notch at their anterior point of junction with the mantle, 
by which they have greater extent of motion, and they terminate in a very thin semicir- 
cular free margin. The fins are supported by two firm crescentic cartilaginous plates, like 
scapule, which play freely on the outer surface of the mantle, and thus give great extent 
and effect to the motions of these powerful dorsal arms. An outer and inner layer of 
muscles, in form of minute white fasciculi, are seen to pass from the middle of the dorsal 
part of the mantle to be attached to these cartilaginous scapule, and singularly resemble 
the mode of attachment of the anterior extremities of Vertebrata. The syphon is here 
| Fig. 5. * Fig. 5. 
