( 11 ) 



tion, also reduced to ^rd natural size. Similar lettering applies to each 

 figure : Z., lung ; (i., diaphragm ; pc, pericardium ; r. v,^ right ventricle ; 

 I. v., left ventricle ; r, a., right auricle ; I, a,, left auricle ; p., pulmonary 

 artery ; ao,, aorta ; v, c, vena cava ; g. I., enlarged patches of lymphatic 

 glands ; Fgl., special pair of pulmonary glands ; t. h., thyroid gland ; tr., 

 trachea ; p. n, pneumogastric nerve ; m., internal mammary artery. 



PLATE XXX. 



Fig. 1. Upper view of the brain of Flatanista, of natural size, and showing 



a symmetry of the cerebral lobes and convolutions. 

 „ 2. Eight lateral aspect of the same brain. 

 55 3. Base of the brain of Flatanista. 2, optic nerve, only a minute thread ; 



55 6, 7 and 8, corresponding nerves of right side ; p., pituitary body ; 



a,, the corpora albicantia ; pv., pons varolii; m., medulla oblongata ; t,, 



temporal lobe ; sy., sylvian cleft. 

 55 4. Mould of the brain cavity of Orcella brevirostris, Owen, \ its natural 



magnitude, and seen from above. 

 55 5. Left lateral face of same cast of the brain cavity. 

 5 5 6. Its basal aspect with impressions of some of the cranial foramina for nerves 



and vessels extant. 



PLATE XXXI. 



Eig. 1. The external genital region and foetus within the left horn of the uterus 

 of Flatanista gangetica. Drawn to scale ^rd natural size : a., anus5 

 the genital slit apparently continuing forwards from it ; m., mammary 

 orifice ; 0.5 ovary ; f., fallopian tube ; /m., its fimbriated extremity ; 

 p., pavilion ; am., amnion ; c, umbilical cord ; t., tail of the foetus twisted 

 in a corner of the sac ; h, points to the minute hairs on the muzzle 

 which afterwarwds are lost ; ^., eye. 



5, 2. A view of the folds from the os uteri internum of a gravid Flatanista, 

 reduced f rd natural size. 



„ 3. A portion of the inner wall of the uterus of P. gangetica showing at f. the 

 entrance of the fallopian tube. Drawn to natural size. 



PLATE XXXII. 



Fig. 1. A virgin uterus of the Gangetic Dolphin, laid open from behind ; natural 

 size : v., vulva dragged apart ; va., vagina ; cf. of., cross and oblique 

 folds; OS., OS uteri externum, with sections of thick mucous folds 

 beneath; u., cavity of the uterus ; /., horn of uterus opened; 0., right 

 ovary; r., rectum. 



