250 DH. J. MUEIB ON THE OEaANlZATION OP THE CAAING WHALE. 



minute point was noticed on a line nearly parallel with and posterior to the angle of the 

 mouth, the eye being above and its postcanthus 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- 

 brans 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 {Lagenorbynclms albirostris), I 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 dimiilutive 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. attoUens, attrahcns, and retrahens'. 



Concemino- 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 acf? Judging from their position and attach- 

 ments (vid. fig. 29), the partially conjoined attrahcns and attollens e\idently 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 abeady ably 

 explained the auditory mechanico-physiological construction in Whales generally; I 

 confine myself therefore to a few loose notes of the parts in 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- 



' Linn. Soc. Journ. vol. si. p. 152. 



