Zoological Society. 305 



in the Dolphins, but diminish to an obtuse extremity. These points 

 of resemblance to the condition of the larynx in the Dugong and 

 Manatee are carried still further in the Mysticete Whale, at least in 

 the foetus dissected by me, and in which both the epiglottis and ary- 

 tenoid cartilages were relatively much shorter, and the thyroid car- 

 tilage larger and more convex than in the Piked Whale (Balanoptera) . 

 The thyroid cartilage is, however, a single piece in both genera of 

 Baleenidae, though deeply notched above and below ; and the larynx 

 presents several interesting individual peculiarities, which, however, 

 the minute and accurate descriptions and illustrations of this organ 

 in both the Balanoptera and Balance, published by Prof. G. Sandi- 

 fort*, preclude the necessity of further dwelling upon. 



" The generative organs being those which are most remotely re- 

 lated to the habits and food of an animal, I have always regarded as 

 affording very clear indications of its true affinities. We are the 

 least likely, in the modifications of these organs, to mistake a merely 

 adaptive for an essential character. The true Cetacea, as is well 

 known, have no trace of vesicula seminales ; but I found these bags 

 present and of large size in the male specimen of our Dugongs. 



" The bones are chiefly remarkable, as in the Manatee, for their 

 dense texture, and the non-development of medullary cavities in 

 them : this reptile-like condition of the skeleton is further exem- 

 plified in the loose connexion of the bones of the head. The bones 

 are not loaded with oil, as in the Cetacea. All the specimens pre- 

 sented 7 cervical and 19 costal vertebra, corresponding to the 19 

 pairs of ribs ; but the number of the remaining vertebra exceeded 

 that ascribed to the Dugong by Home and Cuvier, there being at 

 least 30, making in all 55. The affinity of the Dugong to the Pa- 

 chydermata is thus again illustrated by the great number of the ribs. 

 The lower jaw is articulated to the cranium by a true synovial cap- 

 sule, reflected over cartilaginous surfaces, and not, as in the carni- 

 vorous Cetacea, by a coarse and oily ligamentous substance. 



** It has been suggested that the use of the projecting tusks in the 

 Dugcng is to detach fuel from the rocks to which they adhere : 

 one can hardly, however, assign any important function in relation 

 to nutrition to parts which are limited to the male sex ; but it must 

 be remembered that the function was assigned by a physiologist who 

 supposed that the tusks in question were specific and not sexual 

 characters, and that the imperfect tusks, which are peculiar to the 

 female, were the predecessors of the projecting tusks, and, in fact, 



* Nieuwe Verhan deling en der Koninklik, Niederlandishe Instituut, Deel. 

 iii.p. 224, pi. I.— V. 



Ann. Nat. Hist. Vol. 2. No. 10. Dec. 1838. x 



