On the Anatomy of Balsenoptera rostrata. 299 



Two equal lengths of the dried tendons were then weighed and 

 found to be in the proportion of 815 to 495, which was assumed to 

 be the proportion of their cross sections. The smaller of these 

 numbers is 59 per cent, of the greater — a result that seems to be 

 as near to the foi'mer result derived from the muscles as can be 

 expected iu this class of experiments. 



" On the Anatomy of BaIce7ioptera rostrata, Fab." By Alex- 

 ander Carte, M.A., M.D., &c., and Alexander Macalister, 

 M.D. &c. 



In this paper the authors give an account of the dissection of a 

 young female of the Lesser Fin or Piked Whale, which was cap- 

 tured off Clougher Head, co. Louth, Lreland, on the 8th of May 

 1863. 



After describing its external form, and giving accurate measure- 

 ments of its various parts, the aiithors point out some differences 

 between the relative sizes and positions of the organs of the animal 

 as contrasted with similar parts of those of the same species which 

 have been recorded by previous writers, especially as regards the 

 position of the dorsal fin, which appendage seems to vary in sitiia- 

 tion in different individuals, and show that consequently no value, 

 as indicative of species, ought to be attached to its relative position. 



This is followed by a description of the osteology of the animal ; 

 and attention is drawn to the fact that the body of the axis vertebra 

 is composed, in part, by the displaced body of the atlas, showing 

 that what at present forms the upper half of the centrum of the 

 axis is in reality the centrum of the atlas. 



The myology of the different regions of the animal has been 

 closely investigated, especially the rudimentary muscles of the 

 paddle, which latter the authors have minutely examined. 



The anatomy of the mouth, pharynx, and blowholes is described, 

 and the mechanism by which the functions of respiration and 

 deglutition are performed. In connexion with the laiynx, a re- 

 markable muscular pouch is mentioned as existing, whicli ap- 

 pendage is supposed by the authors to be accessory to the act 

 of expiration, serving a somewhat similar office to that of the 

 air-reseiwoir in a double-action bellows. Directly in front of the 

 glottis there existed a peculiar hood-like fold of mucous membrane 

 arranged in such a way as to allow of its being drawn over the 

 orifice, and so prevent the entrance of all foreign substances into 

 the respiratory tract during the act of deglutition. 



The tongue was found fixed, as far as its tip, by a thick fra?- 

 num. The lateral walls of the submaxillary cavity were thrown 

 into folds, thereby admitting of considerable distention, this ar- 

 rangement being 'peculiarly adapted to the feeding-requii^ements 

 of the animal. The number of baleen plates found in the speci- 

 men was 280 on each side. 



The muscles for acting on the blowholes were arranged in 

 three strata, the superficial and deepest layers being used in 

 opening, and the intermediate one for closing the nasal canals. 



20* 



