DR. J. MURIE ON THE FORM AND STRUCTURE OF THE MANATEE, 163 
attachment ; both pass round the vagina towards the clitoris, partially decussating with 
the fibres of the sphincter vagine. 
In the male, as Vrolik' more particularly has noted and figured, there is a well- 
defined fleshy ischio-cavernosus and long retractores penis. Moreover I readily recog- 
nized a bulbo-cavernosus. While fully developed and normal in attachment, these 
three muscles correspond with the somewhat altered position of the pelvis &c. from 
that of quadrupedal Mammals. 
3. Muscles of the Dermis. 
The superficial fleshy investment to which the name of panniculus carnosus has been 
given, is enormously developed in the Manatee. Indeed, as Stannius justly observes, the 
ventral portion of it represents in a certain degree a supplementary belly-muscle, sup- 
plying the voluminous entrails with an additional powerful support, which is so much 
needed owing to the extraordinary shortening of the rib-cartilages. In the female, as 
also to some extent in the younger male, the depth of muscle varied in different regions. 
The muscular fibre in the former specimen, at its posterior abdominal or genital portion, 
had a thickness of 14 inch; but further forwards, towards the middle of the body, it 
decreased to 0°6 inch, thinning upwards on the back to 0-2 inch or thereabouts. On 
the side of the neck it equalled the midventral part in volume, thickening considerably, 
however, on the side of the cheek. 
Although the panniculus forms a uniform whole, I shall prefer, for several reasons, 
to describe it piecemeal. 
As indicated above, the extensive panniculus carnosus forms a great broad fleshy 
wrapper of longitudinally directed fibres, covering the entire abdominal surface (P.c') 
from the pectoral limbs backwards to beyond the anus (P.c***). On the side of the 
posterior half of the body the muscle stops short of the tips of the ribs, where part of 
the external oblique is exposed; but forwards from this it rises higher, the fleshy 
part reaching almost to the level of the vertebral border of the scapula. The line of 
demarcation of this lateral or costal border, however, is not so abrupt, as exhibited in 
fig. 8, Pl. XXI., but trends, and is lost dorsalwise in a strong aponeurotic fascia. The 
muscular fibres of the outer shoulder portion pass forwards along the neck and side of 
the cheek, and partly become inserted by aponeurosis on the broadest surface of the 
malar bone, and, partly fleshy, are continued onwards and commingle behind the angle 
of the mouth with a deeper throat-layer of the muscle presently to be described. 
A few inches behind the axilla the belly portion of the panniculus splits into two 
segments, the outer or upper fork of which is that already spoken of as covering the 
outer surface of the shoulder. From this a slip runs towards the humerus (P.c*). 
The inner sternal fork, at its divarication, possesses an external tongue-shaped corner 
(P.c**), mesially to which the muscle lies over the sternum (in the female being 
1 Bijdragen, p. 77, pls. 5 & 6. figs. 22, 23, , d. 
