PLATANISTA. 433 



Vertical sections through the dermal and subcutaneous tissues of part of the 

 snout (PL XXXVI, figs. 2 and 3, and see also PL XXXI, fig. 1^) demonstrate the 

 usual constituents, save the absence of sudoriparous and sebaceous hair glands. 

 The papillae of the vertically descending epidermal layer are stout, and not quite 

 uniform in length, the shorter ones being rather conical, the thicker slightly club- 

 shaped, a few having bifid extremities. The corresponding ascending papillae of 

 the corium have a copious capiUary supply derived from the rather numerous blood- 

 vessels of the deeper tissues. Where the hair-like bristles have been cut through 

 obliquely (fig. 2 h,) in the sections made from the foetal specimen of Flatanista, 

 their walls are thick, and surrounding them is a wide circular and dense fibrous 

 area, the outermost wavy elastic fibres of which mingle with those of the neighbouring 

 connective tissue. The superincumbent half of the fibro-vascular layer of the corium 

 has but few traces of oil particles intermixed, but in its deeper half, the fatty 

 particles and oil globules preponderate, and are both very numerous and characteris- 

 tic, as large elliptical areas. In many of the larger-sized oil globules, bundles of 

 needle-shaped and stellate crystals present themselves. In this snout-section, the 

 fibres of the subcutaneous tissue, both strong and glistening, form often a lozenge- 

 shaped mesh- work, and deeply become stouter, as bundles of broader bands inter- 

 lace freely and enclose in layers the fatty constituents above spoken of. Below the 

 blubbery layer comes a layer of ordinary connective tissue, the masses of striated 

 muscular fibres joining this again. 



Mouth. — On opening the mouth of Flatanista, its form is seen to be trian- 

 gular, the base of the figure being placed posteriorly. The upper lips have a 

 sharp edge and crescentic outline, the convexity looking inwards and downwards. 

 The anterior end of the upper lip is prolonged forwards to the external margin 

 of the alveolar line of the teeth of the snout, and its posterior end is under the 

 eye. The upper lips are not supported by bone, but consist of the strong fibrous 

 tissue that fills up the interspace between the maxillary laminae, and the lower 

 limit of which extends from the preorbital process of the frontal to the side of 

 the dental portion of the superior maxilla opposite to the twenty-third tooth. The 

 lower hps are round, fleshy, and concave from before backwards, and are overlapped 

 by the sharp edge of the upper lips. The inner margin of the upper lip is devoid of 

 pigment, but the under lip has more or less the colour of the external skin. The 

 jaws are capable of great extension, opening at their tip, in a specimen nearly 6 J feet 

 long, to 13 inches, the distance between the angles of the mouth being 4 inches, the 

 anterior breadth being only 0'65 inch. The interior of the mouth and the palate 

 are quite smooth in the half-grown individual, but, in the adult, the sides of the 

 mouth from the angles are thrown into strong longitudinal folds which extend 

 back to the fauces. In the same individual the faucial region measures 2*50 inches 

 across and 1'75 inch in vertical capacity, which, however, is doubtless greatly 

 increased when the tongue is drawn down. 



Tongue. — In this fluviatile dolphin, the lingual organ is well developed. It is 

 firmly attached at its tip by a fold which runs forward to the symphysis of the lower 



g3 



