372 CETACEA. 



upper lip has a sharp margin, and the interval hetween it and the line of upper 

 teeth is concave from without inwards, broad behind at the last tooth and narrowing 

 anteriorly to a point. A deep furrow runs from the symphysis of the lower jaw to 

 the base of the tongue, and numerous folds pass from it along the sides of the 

 tongue, to the angle of the mouth. The deep furrow and the folds in these localities 

 like others presently to be described on the palate in the faucial and pharyngeal 

 regions and oesophagus are all represented in the foetus, so that they are structural 

 characters developed to confer expansibility on these portions of the digestive tube. 



The tongue of this genus (figs. 1 and 2, t.) is free as far back as the beginning of 

 the posterior fourth of the interdental space of the lower jaw, and in this respect 

 it differs remarkably from the character of this organ in Cetacea generally. It is 

 a long spatulate structure with sharp free borders which shelve rapidly down- 

 wards and backwards, and it is slightly contracted opposite the angle of the mouth 

 and somewhat dilated anterior to that, terminating in a rounded but pointed end, 

 external to which the margin is crenulated for a short distance both in the foetus 

 and in the adult. Behind the angle of the mouth, it is concave from before 

 backwards and slightly raised and swollen into two basal eminences. In the foetus 

 the anterior portion is more or less concave from side to side, which is to a cer- 

 tain extent also the character of the organ in the adult. In the foetus there is 

 a fold corresponding to the frsenum linguae, but it disappears when it is laterally 

 stretched and returns when the parts regain their natural position. In the adult, 

 however, there is no fold determinable in this locality. In the foetus the organ 

 measures 4 inches from the anterior end of the frsenum epiglottidis to the tip, 

 and it is free for one-third of its extent. In the adult, the tongue to its 

 base is 6' 85 inches long and 1"*90 in its greatest breadth. In the foetus there 

 is no indication of a raphe, and indeed so far from such a furrow existing, the 

 middle of the tongue anteriorly is slightly raised, as two shallow and feeble fur- 

 rows run backwards from the first crenulation external to the triangular tip. 

 In the adult, however, a short raphe begins opposite the angle of the mouth, 

 and running backwards for about one inch terminates in a transverse fold, which 

 curves forward from angle to angle of the mouth and corresponds to the limit 

 of the extrinsic muscles of the organ, but which does not show in the foetus. 

 On either side of the raphe there are many wavy longitudinal folds which become 

 curved on the attached portion of the tongue, anterior to them the convexities of 

 the curves being forward, and these folds are feebly marked in the foetus. Imme- 

 diately posterior to the deep transverse fold there are similar feebler folds which also 

 exist in utero, and before the basal eminences in the foetus, the dorsum of the 

 organ, as in the adult, is covered with convoluted folds. I have failed to detect 

 the orifices either of sublingual or submaxillary glands or the openings of any glands 

 whatever on the under surface and sides of the free portion of the tongue. In the 

 adult the margins of the tongue superiorly and the whole of the dorsum, within an 

 inch of the tip, as far back as the transverse fold, are covered with the orifices of 

 mucous glands. Behind the transverse fold, less numerous, but much larger and 



