1901.] LARYNX OI? CERTAIN WHALES. 297 



parallel to the long axis, and, as we have seen, forms the lateral 

 margins of the entrance to the larynx, which, according to Dubois, 

 corresponds to the " glottis" — the rima glottidis of human anatomy. 



In the case of Coyia this process is less distinctly marked off 

 from the rest. 



Two further points of interest occur within the Cetacea, viz., 

 the great ventral, sublaryngeal pouch in the Mystacocete, and the 

 peculiar aryteno-epiglottid tube of the Odontocete. 



I have already referred to the view that the sublaryngeal pouch 

 of the Mystacocete is, in part at least, derived from the thryo- 

 arytenoid muscle ; the great downward " sagging," so to speak, of 

 this muscle, so as to project between thryoid and cricoid cartilage, 

 has led to the oblique and nearly vertical position of the 

 " glottis " — the wide entrance to the lai-yngeal chamber. 



This glottis is approached, in these Whales, by a comparatively 

 wide, short canal, owing to the loose connection between the 

 arytenoids and epiglottis. 



But in the Odontocete these cartilages are very heavily built, 

 especially at the lower ends ; and that of the epiglottis projects 

 much further into the larynx than in the other group, so that the 

 entrance is reduced to a narrow cleft, and the glottis itself is 

 greatly blocked up by the lower end of the epiglottis. Further, the 

 glottis is not so definitely marked out as in the Mystacocete ; it 

 can be located only by the position of the thryo-arytenoid 

 muscle. 



One is tempted to see some interrelation between the " pouch " 

 and the "tube"; to think that in some way the junction of the 

 pouch of the Mystacocete is taken on by the glottideal tube and 

 the elaborate " spiracular sacs " of the Odontocete. And this leads 

 us to look for any homologue in the Odontocete of the sublaryngeal 

 pouch of the Mystacocete. 



The latter, as is known, is a median, ventral evaglnatiou of the 

 muscular wall of the larynx, between the thryoid and cricoid 

 cartilages ; in position it is post-thryoideal. 



But in the Odontocete, no outgrowth occurs in the same re- 

 lative position. It is true that in various genera — e. g. Mesoplodon, 

 Beluga, Orampus — a small median sac has been described by 

 various authors; but this sac has glandular walls (a few muscles 

 are mentioned by Murie), and at any rate occupies a different 

 position, viz., between the base of the epiglottis and the upper 

 (anterior) border of the thyroid cartilage. In fact, it is pre-thy- 

 roideal in position. 



Nevertheless, Murie, Watson and Young, and Sir W. Turner, 

 regard this sac as homologous with that of the Mystacocete, and 

 Dubois agrees with them, und, further, includes in the homology 

 small, lateral, glandular outgrowths which occur in some genera 

 (no doubt the conditions represented by Gogia). 



Now, lateral outgrowths in this position — at the sides of the 

 base of the epiglottis and projecting, more or less, over the upper 

 margin of the thyroid, either actually or morphologically — are 

 known in a great variety of mammals. In some cases the two 

 sacs or "ventricles of Morgagni"are near together and close to 



