288 PROP. W. B. BENHAM OK THE [-^PI"* 2, 



II. The Larynx of Cogia. 



From the few references to this small Cachalot that I have been 

 able to discover, I gather that very little is known of its viscera. 

 The larynx agrees on the whole with that of other Odontocetes 

 hitherto described in detail, bat in certain points — as, for instance, 

 and in particular, iu the duplicity of the thyroid cartilage — 

 it appears to be unique amongst the Cetaceans, at least so far as 

 is indicated in the small amount of literature available and 

 references therein. 



The specimen to which this larynx belonged had, as I have stated 

 above, been cut open and injured in various ways before I was able 

 to obtain possession of the carcase, and the larynx itself had been 

 cut through and severed from the pharynx and from the hyoid 

 bone, hence I am unable to give an account of the relations of 

 the organ to the neighbouring parts ; but, as these are well known 

 for se^eral other genera, this deficiency is of little importance. 



The general form of the larynx is seen in the accompanying 

 drawings (PL XXV. figs. 4, 5, PI. XXVI. fig. 6). It has a greater 

 diameter dorso-ventrally than laterally, which is the reverse of the 

 condition in Balanoptera and in Globiocephalus melas, according to 

 Murie (1867). Its dorso-ventral diameter (3 inches) is much 

 greater than that of the trachea (1| inches), so that the postero- 

 ventral margin projects considerably and forms a veritable "pomum 

 adami." 



From the upper and anterior end of the larynx the conjoined 

 arytenoids and epiglottid cartilages project as a distinct tube, and 

 this characteristic Odontocete tube is directed upwards and 

 forwards towards the dorsal surface ; this makes a very distinct 

 angle with the longitudinal axis of the laryngeal cavity, whereas 

 in the Eorqual the arytenoids and the epiglottis diverge from one 

 another, each forming an angle with the axis of the larynx, but 

 in opposite directions. 



The "aryteno-epiglottidean tube " projects upwards from the 

 floor of the pharynx for about 1^ inches. The upper end is 

 thickened so as to be firmly clasped by the velum palati and retained 

 within the narial canal ; it had been cut away from its natural 

 position, so that the relation of the end of the tube to the nares could 

 not be ascertained, though there is no reason to believe it to be 

 different from what has been described for other Odontocetes. 

 The aditus laryngis (PI. XXVII. fig. 20), when stretched to its 

 fullest extent, is somewhat rectangular, with thickened, rounded 

 margins ; the lateral margin on each side is formed by the thick 

 and fleshy " aryteno- epiglottid " fold, which reaches upwards to 

 the apex of each of the cartilages concerned ; the dorsal margin 

 by the rounded edges of the two arytenoid bodies, which are 

 continuous along their dorsal surfaces right to their tips, and are 

 in strong contrast with those of Balcenoptera, for in place of their 

 lamelliform separable plates, we have in the Odontocete a thick, 

 rounded or continuous fold. The ventral margin of the aperture 



