146 DR. J. MURIE ON THE WHITE-BEAKED BOTTLENOSE. 



The next definite assertion as to the point from specific exami- 

 nation, that I know of, is that of Dr. Knox, who, in his ' Cat. Prep. 

 Whale ' (1828), says of his specimen No. 3, taken from Balcena 

 wiaximus borealis — Physalus antiquorum: — " The preparation was 

 cut out of the enormous mass in which the condyles of the lower 

 jaw move ; and, of course, all the surfaces presented to view are 

 cut surfaces. The texture is distinctly fibrous ; but the fibres are 

 so intimately interwoven together as to defy any attempt to 

 make out an exact arrangement. It did not contain much oil, 

 and was cut with extreme difficulty, the most powerful knife 

 making its way through it as through a portion of caoutchouc." 



More lately, 1861, Eschricht and Bernhardt * announced their 

 discovery in the foetus and very young Greenland Whale, Ba- 

 lcena mysticetus, of a double synovial capsular infram axillary 

 joint, and supposed they " must also be found in older individuals 

 of the same species." 



Hunter's and Knox's observations, however, have been corro- 

 borated by Carte and Macalisterf in the adult Pike Whale, Ba- 

 Icenoptera rostrata. 



It would seem, therefore, that in the adult stage at least- 

 three genera, two whalebone and one toothed Cetacean (Physalus, 

 Balcenoptera, and Lagenorhynchus) ,have no synovial capsular arti- 

 culation of the lower jaw. Whether it exists in their foetal and 

 young condition and in other species is a matter of uncertainty, 

 as is the reverse or its presence in the adult and old Eight Whale. 



The muscular structures which most powerfully influence the 

 movement of the lower jaw are the pterygoides. The external 

 one of these is strong, entirely fleshy, arises forwards almost 

 within \ inch of the last upper tooth ; its mandibular insertion 

 is around the inferior dentate foramen. 



What represents the levator palati is strongly fleshy in front, 

 narrowing very much behind, latterly ending in a fibro-tendinous 

 portion, which is inserted into the post-inferior surface of the 

 tympanic bone. 



5. The Blow-hole and its diverticular chambers. — The ex- 

 ternal narial orifice or spout- hole has a breadth of 2| inches. 

 The front lip has a crescentic convexity forwards ; but the hind one, 

 with somewhat of a mesial peak, bluntly pouts forwards, so as 

 to produce shallow bilateral concavities. The membrane within 



* ' Om Nordhvalhen,' Kay Soc. Transl. p. 85. 

 t Phil. Trans. Roy. Soc. 1868, p. 212. 



