144 DR. J. MURIE ON THE FORM AND STRUCTURE OF THE MANATER, 
Manatee. Here we find that definition into separate or individual muscles is not easy, 
from the very fused condition of the parts. There may be traced, however, through the 
length of the dorsal and what constitutes the lumbar region oblique sets of fibres 
which answer to those of the multifidus spine and semispinales. 
The levatores costarum, corresponding to the number of ribs less one, are more easily 
defined than the preceding; but they also have their fibres much intermingled with the 
long spinal muscles presently to be spoken of. 
As regards the énterspinales, these either are aborted or so masked by the volume of 
interspinal yellow elastic ligamentum subflavum that their function is supplanted by 
the latter. 
From that close adherence of the mass of the erector spine to the tissues beneath, 
intertransversales muscular slips are chiefly apparent in the lumbar and caudal regions, 
reference to which shall be made further on. 
What corresponds to the combined or continuous spinalis dorsi and levator caude 
internus is a long, narrow, but, in the back, vertically deep muscle, which runs from 
the neck backwards as far as the end of the tail. Anteriorly, where laterally com- 
pressed but fleshy, it fills vertically the hollow between the cervical spines and trans- 
verse processes. Posteriorly it becomes tendinous and aponeurotic, and is fastened to 
the caudal vertebre superiorly. 
There is a very massive and in great part fleshy longissimus dorsi, which extends 
outside the last from the first rib backwards to the very end of the caudal vertebra, 
thus including what constitutes the levator caud@ externus of most other Mammals. 
Like the preceding the tail-tendons are interwoven into an aponeurosis, partially fixed 
to the transverse and to the spinous processes. 
The well-marked sacro-lumbalis is a rather narrow but thick muscular elongation, 
lying upon and firmly attached to the whole of the ribs outside their angles. Its outer 
tendons are short and fixed to the coste along with the fleshy part of the external 
border of the muscle; the internal tendons are even more imbedded among the mus- 
cular substance. At the first rib the sacro-lumbalis is very narrow, but is broader 
towards the middle of the body—in the larger specimen being 2 inches in transverse 
diameter. At the last rib there is a fusiform muscle, almost like a continuation of the 
sacro-lumbalis, but which I shall describe along with the subcaudal series. A few 
fleshy fibres are continued forwards on to the axis, from the sacro-lumbalis, and a still 
larger amount from the longissimus dorsi; but, as might be expected from the remark- 
able shortness of the Manatee’s neck, neither of these compressed bundles is of much 
import functionally. ‘They are individually homologues of the cervicalis ascendens and 
transversalis colli. p 
There is, moreover, a better representative of the trachelo-mastoid, which is a much 
longer and distinct muscular band, proceeding forwards from the edge of the trans- 
versalis colli, and is inserted into the skull. The cranial attachment is upon the 
