416 DR MORRISON WATSON AND MR ALFRED H. YOUNG 
both in Globiocephalus melas and in Balenoptera rostrata, but inasmuch as 
in the last named these arise from the body of the hyoid bone, there is a 
difference of origin in the two species. In Beluga, on the other hand, as 
previously described, the two parts are fused into a single muscle. CARTE and 
MACcALISTER* consider that three aryteno-epiglottidean muscles exist in Bale- 
noptera rostrata, whilst in Balenoptera Sibbald, TurRNERt found but one. 
Muriet affirms his inability to distinguish them in G'lobiocephalus melas; in 
Beluga they are certainly absent. 
Exterior of Laryne. 
The free larynx projects upwards from the floor of the pharynx, and 
measures 3} inches in length. Flattened from side to side, and broad at its 
base, it is slightly constricted in the middle, and again expands, both as regards 
its antero-posterior and transverse diameters, at the apex. The epiglottis is 
rather higher than the arytenoid cartilages, in which respect Beluga differs both 
from G'lobiocephalus melas and Lagenorhynchus, in which the reverse is the 
case. The epiglottic section, broader than the arytenoid, is slightly curved 
transversely, so that the latter cartilages are to some extent embraced by the 
former. The posterior segment of the apical portion of the larynx, formed by 
the arytenoid cartilages, presents an emarginate notch similar to that described 
by Muri in Globiocephalus melas. The internal borders of these cartilages are 
in contact along the whole length of the tubular larynx. The upper opening of — 
the latter is broad transversely, and furnished with an anterior and posterior 
thickened lip of mucous membrane, inclosing horn-like processes of the epi- 
glottic and arytenoid cartilages respectively. A linear depression extends 
from base to apex of the lateral aspect of the organ; it indicates the borders 
of the epiglottidean and arytenoid cartilages, whilst another groove marks 
posteriorly the apposition of the arytenoid cartilages. 
Interior of Larynx. 
There is a complete absence of the true vocal cords ; an appearance of such — 
at first sight certainly exists, but upon more accurate examination this simula- — 
tion of them is found to be due to the projection inwards of the sharp inferior — 
borders of the arytenoid cartilages. It is, however, by no means improbable, 
as MrckeEL§ states, and with this view Dr Murte|| coincides, that these sharp — 
edges may serve the purpose of vocal cords in the cetacea. The mucous 
membrane lining the posterior wall of the larynx is thrown into numerous 
longitudinal folds, whilst at the base of the epiglottis it is projected forwards, 
so as to form on each side of the middle line a pouch of size sufficient to admit 
* J, pp. 237,238, +XVILp. 237. tILp.264. §XVIIL p.596. || X.p. 129. 
