250 DR. J. MURIE ON THE ORGANIZATION OF THE CAAING WHALE. 
4) 
minute point was noticed on a line nearly parallel with and posterior to the angle of the 
mouth, the eye being above and its posteanthus nearly equidistant between them. As 
further dissection was proceeded with, the external auditory canal or meatus became 
more apparent, and was found to be, as in other Cetacea, a cord-like tube as thick as a 
goose-quill. It was at first directed horizontally inwards, on a level with, but behind 
the articular condyle of the mandible. Slightly widening it quickly resumed its calibre, 
and by three several spiral turns, or winding S-ways, it reached the foramen and mem- 
brane on the outer side of the inflated tympanic bulla, at this point being situate 
immediately above and in front of the cranial attachment of the stylo-hyal. The 
auditory tube, though in one sense free, was nevertheless retained in its position 
throughout by dense fibrous tissue and the other padding of the outer cranial wall; but 
at the upper ends of the spiral turns muscular fibres were fixed to it, of which more 
presently. 
Among the many writers on Cetacean anatomy, Von Baer alone I find mentions the 
existence of rudimentary muscular fibres in the Porpoise, appertaining to the external 
auditory apparatus. In my dissection of this female Caaing Whale, and still better in 
the fleshy adult male White-beaked Bottlenose (Lagenorhynchus albirostris), 1 have been 
fortunate in discovering, not indeterminate fibres, but three well-developed muscular 
slips, attached to and acting upon the cartilaginous tube of the meatus. These might 
either represent the diminutive muscles of the helix and tragus of higher Mammals, or 
more probably, and as I take them to be, they are the homologues of the auricular 
muscles, in spite of the absence of an expanded pinna. Accordingly I have already 
named them as external muscles of the ear, viz. attollens, attrahens, and retrahens'. 
Concerning the action of these muscles, one would think their functional subservience ~ 
to the organs of hearing would be very slight. ‘They have no outer pinna to move; 
how or in what way therefore do they act? Judging from their position and attach- 
ments (vid. fig. 29), the partially conjoined attrahens and attollens evidently drag both 
forwards and upwards the outer portion of the auditory tube, particularly the wider 
horizontal segment. The retrahens, while elevating, or, it may be, very slightly tugging 
the tube backwards at its root, would also, at the same time, horizontally straighten it. 
These movements, though of the most constrained description, may serve a purpose in 
audition. 
As a precautionary measure, in case of loss of the small ear-bones in transmission of 
the skull abroad, they were left attached; I had no opportunity, therefore, to examine 
thoroughly the organ of hearing. ‘The gifted Hunter and others have already ably 
explained the auditory mechanico-physiological construction in Whales generally; I 
confine myself therefore to a few loose notes of the parts im situ (fig. 31). 
The tympanic bulla, which in this inferior aspect has a long oval outline, with a 
capitulate pedicle (malleus?) about the middle of its outer margin, lies obliquely for- 
1 Linn. Soe. Journ. vol. xi. p. 152. 
