248 DR. J. MURIE ON THE ORGANIZATION OF THE CAAING WHALE. 
than in the old Lagenorhynchus, nevertheless offered more appearance of separation in 
the latter (vide figs. 63, 64, N/). The combined action, however, agrees, viz. protraction 
and retraction of the lips of the blow-hole, according as the longer anterior or shorter 
fan-shaped yertical fibres contract, and also, coincidently, compression or dilatation of 
the premaxillary sac. 
A dilator naris, retractor ale nasi (sew pyramidalis plus constrictor naris, =com- 
pressores naris), and depressor ale nasi muscle, in superincumbent planes, besides a 
vomerine and alar fibro-cartilages, are described by Carte and Macalister as existing in 
Balenoptera rostrata’. Whether they or I have interpreted the structures correctly 
future investigators must decide. But as regards the muscles I would note that the 
attachments and numbers of layers more truly belong to the entire facial set of land 
Mammals than are only restricted to the homologues of the nasal group, 
3. Skin and Subcutaneous Coverings —The skin over the entire head is very thin, 
hardly exceeding 0:1 of an inch; and the superficial film of cuticle has only a thickness 
of about 7$>5 of an inch. Beneath the skin proper, and corresponding to the subcu- 
taneous tissue of other Mammals, is a dense fibro-elastic tissue, composed of innumerable 
reticulations of white glistening fibres, intermingled with fatty or oily material. Some 
of these fibres are stronger and more prominent than others, so that, as seen in vertical 
section (fig. 26), there appears to be an irregular meshwork of thickish and more delicate 
thread-like fibres laid together, warp-and-woof fashion. Some are directed longitu- 
dinally, others transversely, and others again entwine obliquely to the cord of the nasal 
prominence. Here and there between the fibres white puncta manifest themselves. 
these being nothing other than cross and tangential sections of the fibrillee themselves. 
The entire body, side of the head, and throat in G@. melas has an enyelope of pale 
yellow-coloured fat, similar in consistence to that found in the same situation in the 
Porpoise. This fat thins as it approaches the root of the tail, and upon the caudal 
expansion is lost in the strong fibrous substance of which that organ is composed. 
On the body generally the fat has a depth of from 1 to 1} inch. In some parts, for 
example the throat and the chest between the pectoral limbs, it is even more. Where 
the latter become free it diminishes; and quite on these appendages it is barely recog- 
nizable. Indeed, on the limbs strong fibrous, almost gristle-like substance takes its 
place; and this latter, towards the free extremity, becomes itself so reduced in quantity 
that at the point only a very thin layer of fibro-membrane intervenes between the upper 
and lower dark-coloured external tegument. Upon the back, in front of the dorsal fin, 
the fatty tissue is more interwoven with fibres, and finally, in the fin, resolves itself into 
dense, firm and elastic texture, truly more cartilage-like than fibrous. 
Regarding the function of the semirigid dorsal fin in this and some of the allied 
genera we have not the remotest conception, unless balancing of the body in the 
watery element has something to do with it. But it does not seem a necessary 
' See their chapter on its “External Nares,” /. c. p. 238. 
