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DR. J. MURIE ON THE ORGANIZATION OF THE CAAING WHALE. 247 
an upper lateral, alar, and rudiment of sesamoid are there. Quite within the narial 
passages on each side of the cavity, partially below but vertical with the alar cartilage, 
is a small globular bag which opens by a fissure into the nares. This sac, which I have 
named the maxillary sinus, is fibrous, smooth, yet glandular within, and contained 
sebaceous or ceruminous-like substance. Still higher on each side, and lying between 
the maxillary, turbinal, and lachrymal bones, and therefore nearer the nasals, is another 
semilunar depression or shallow sinus 4 inch long, nearly vertical, though somewhat 
crescentic. A third and much better marked cavity exists on the floor of either moiety 
of the nares. This, a slipper-shaped fossa or sinus-like fold, is sunk forwards, or pro- 
duces a well defined step about an inch long betwixt the deeper postnarial chamber and 
the more raised floor of the anterior segment of the interior nares. The two last- 
mentioned pairs of fossa are each smooth-surfaced and lined by a continuation of the 
moist mucous membrane. Anteriorly the nares are capacious, and under control of the 
flabby but muscular parietes. 
Secondly, as regards the Tapir, the late Mr. H. N. Turner’ has shown, and a dissection 
on my own part? verifies, that quite within the nose, in the semicircular notches outside 
the projecting nasal bones, are two long, smooth-lined sacs or naso-frontal maxillary 
sinuses. Each of these is somewhat f-shaped, the blind and bulbous posterior extremity 
being curved inwards, the anterior straighter end freely communicating with the interior 
nares. These elongate sinuses are mainly hollowed out of what ‘Turner supposes to be 
the lateral nasal cartilages, continuous with the septal. He thinks alar cartilages are 
absent; in this I do not quite agree. The muscles of the proboscis are arranged after 
the usual type of the nasal group, with a special pair of long levators. 
I refer the reader to my illustrations and account of the anterior cranial muscles of 
Lagenorhynchus albirostris and Grampus rissoanus, and the figures 63 to 67 of the 
present plates, in lieu of redescription. ‘The latter has one layer less than the former, 
and the diminutive fasicles connected with the naso-facial canal are not so markedly 
differentiated. 
As regards the action of the different layers in Globiceps &c., they are nearly identical 
in the several forms. The superior layer is a dilator of the blow-hole and compressor of 
the maxillary sac; the second sheet assists the first. The third set of fibres assimilates 
to the preceding in its use; but there is an additional mechanism of the parts induced 
by its upper anterior tendinous slip. This runs quite into the nasal blubber; and the 
fibres cross well over, so that, while creating tension of the fatty nodosity, a certain 
amount of backward pressure follows, and aid is lent to the elastic fibrous cushion which 
usually keeps the commissure of the nasal orifice closed. The small, short, and semi- 
circular muscle connected with the posterior canal acts as a retractor and compressor to 
it. What I have termed premaxillary or naso-labialis, while less fleshy in G. melas 
1 P. Z.8. 1850, p. 103. 
2 Rhinocherus sumatranus, Journ. of Anat. & Phys. vol. vi. p. 138, and figs. 8 & 9, pl. x. 
