450 CETACEA. 



essentially departed from, althougli slight variety obtains. Among the Delphinidce 

 and GlobicephalidcB, with a transverse outer slit, a pair of oval pads rest against the 

 hinder wall, and a small cartilage laterally approximates. The vertical passage 

 descending to the two inner narial orifices sends forwards along the premaxillaries 

 either a single one or a pan- of elongated sacs. These thus bend round deeply below 

 the facial blubber mass. From the spiracular cavity higher up, in some instances 

 very superficial, a large thin-walled sac diverges outwards on either side. By an 

 opening close by each of the latter, a narrow, often cord-like sac or tubular canal winds 

 backwards and inwards, or sometimes even has a twist forwards. Thus, there are three 

 pairs of sacs, differing in position and shape, all communicating with the spiracular 

 cavity : a pair of pads or fibroid eminences, and a pair of rudimentary nasal cartilages, 

 besides a medial septal cartilage. 



Now, the same structures are obvious in Flatanista. The longitudinal direction 

 of the spout-hole produces therewith a very obliquely shelving anterior wall, and 

 thus the boss roofing the elongated premaxillary sac appears to jut more upwards 

 and backwards than in those Cetacea with a cross blow-hole. This boss, or anterior 

 cushion, consists of very firm fibrous tissue, intermingled deeply with flleshy fibres, 

 forming a premaxillary muscle. The latter again in front commingles with coarser 

 reticulate fibroid tissue, between the meshes of which oily blubber is retained. Thus, 

 the cui)ular eminence of the face, at the sides supported by the porous maxillary 

 crest plates or arches, is composed of coarsely reticulate glistening fibroid tissue, 

 with oily matter distributed in it. It is much firmer than in those Whales in which 

 it assumes the constitution of true blubber. Below the mass in question is the pre- 

 maxillary sac {iDOod-ctd, Eig. 15, I) ; trending forwards, and connected therewith is a 

 small outer recess. This latter (II), though much more deeply situated than in the 

 Dolphins and Porpoises, evidently corresponds to their superficial lateral sac. Just 

 behind and towards the inside corner of the bony narial aperture a small opening 

 leads into a diminutive passage (III) curving outwards, and round a pad and gristle 

 presently to be mentioned. The said pad {p) is a nodular mass of solid fibrous 

 tissue, overhanging the nasal passage. Immediately outside it, starting apparently 

 from the frontonasal region, and following the course of the upper premaxillary 

 process is a crescentic strip of cartilage {go) . This is externally convex and internally 

 concave, prominent behind and shooting downwards and forwards, outside the 

 anterior boss already spoken of. The passage to the nares lying between them, but 

 outside the cartilage, is a shallow crescentic depression subsidiary to the narial 

 channel. 



The cartilage is covered by fibrous tissue, and muscular fibres connect it outside 

 and in front with the fleshy tissue distributed round the spiracular cavity 

 generally. 



The interior of the narial chamber, except the sacs, is lined with dark pigmental 

 tissue, and in the more upright portion of the walls is thrown into narrowed wavy 

 corrugations which doubtless are effaced on dilatation of the chamber. I may 

 further call attention to a little glandular recess situated on the inner whorl of 



