( 15 ) 



Fig. 5. A magnified view of a special section of a tooth of a young Gangetic 

 Dolphin. It shows a complete enamel (e.) layer, and the centre com- 

 posed of characteristic dentine {d), 



5, 6. Adult tooth of Flatanista, from the middle of the lower jaw, in vertical 

 section. About twice natural size. 



5, 7. Ditto of a tooth behind the middle x 2 diameters. 



5, 8. Ditto from the posterior third of the row, about 2 diameters. In the 

 three last figures e. signifies enamel; c?., dentine; ando. c?., osteo-dentinel. 



„ 9. A thin transparent longitudinal, vertical section of the eye-ball and 

 surrounding soft textures of a full grown Flatanista, and of natural size. 



„ 10. The same section enlarged about 6 times and showing the various parts 

 as follows: — e,, eyelids, with thick pigmental papillary skin cover- 

 ing ; m., cut muscular fibres of the palpebrse, imbedded in firm fibrous 

 tissue ; <?., cornea and its conjunctival covering ; a,, aqueous chamber ; 

 2?., vitreous chamber and humour ; I., position which the lens should 

 occupy ; i., iris ; ch., choroid coat ; 5., sclerotic ; ojp,, optic nerve ; /., fatty 

 envelope of eye-ball ; ^., gland. 



„ 11. A transverse section of the umbilical cord of Flatanista, enlarged twice 

 natural size : ^., arteries ; v., one of the umbilical veins ; u., urachus ; 

 g, 5., glandular body ; v. s., vascular spaces. 



„ 12. Vertical section through the wall of the first cavity of the stomach of 

 P. gangetica, enlarged 4 times natural size. 



„ 13. A strip of the same vertical section of first stomach more highly magnified : 

 ep., epithelial layer; ^., glandular layer ; c?., connective tissue layer or 

 submucous coat ; m., muscular layers ; fs,y fibroserous coat ; v,^ blood- 

 vessel. 



„ 14. A vertical section through a portion of the wall of the first gastric cavity of 

 Orcella hrevirostris : ep.^ epithelial layer ; c, ^., columnar layer or mucous 

 glandular layer ; c, connective tissue of submucous coat x 10 diameters. 



„ 15. Vertical section of the wall of the second gastric cavity of Orcella: ^., 

 glandular layer; c, connective tissue or submucous coat; a., thick- 

 walled arteries piercing same, and shown both in transverse and deeper 

 in oblique section. Highly magnified. 



„ 16. An enlarged view of portion of a vertical section of the pale piece of the 

 ductus communis choledochus of 0. hrevirostris, about 20 times natural 

 size : g,, glandular and epithelial layer ; (?., layer of connective tissue 

 (submucous coat) ; m., muscular layers ; fs,, fibroserous investment. 



PLATE XXXVII. 



Microscopical structural peculiarities of the glands of the stomach, the lungs, 

 the larynx, the female genital organs, and placenta of Orcella and Flatanista — 

 Fig. 1. A vertical section of a small piece of the upper layer of mucous membrane 



