394 CETACEA. 



wliicli in this aspect is a sliacle larger tlian either liinder extremity of the cerebral 

 hemispheres. The medulla spinalis is relatively large, and set high in relation to 

 the cerehellnm. 



Erom the foregoing description it would seem that Orcella has a delphin- 

 oid form of brain, comparatively massive, broad, and although in a general way 

 flattish, yet by no means low set. The fronto-orbital lobes are unusually deep, and 

 the anterior brain-facies altogether vertically abrupt in contour. The cerebellum 

 is preponderantly large and in a great measiu-e uncovered both laterally and above. 

 Moreover, as the sequel will show, the brain of Orcella manifestly differs in several 

 particulars from that of Flatcmista, while it strikingly follows the general shape of 

 that of Globicephalus. 



-JBxternal organs of generation (Plates XXXIII and XXXIV).— The cleft of 

 the vulva resembles that of other Cetaceans, the skin around being somewhat 

 smooth and pale coloured. The most characteristic feature is the existence of the 

 well marked perinseum {pe.) already mentioned, the raphe being about IJ inches 

 long, and in this particiUar, Orcella essentially differs from those whales which, 

 being destitute of pelvic bones, have no perineal space. 



The mammary slits (Plate XXXIII, fig. 1 m) are each 0"70 inch long and 

 situated 1'20 inch from the vulva, their hinder ends being 2 '20 inches distant 

 from the anus. The nipple is not prominent, being laterally compressed and 

 placed at the base of the mammary furrow which is comparatively shallow, viz., 

 0"20 inch deep. 



The mammary gland (mg.) has an enormous dUated lactiferous sac, 2 inches 

 long, with a position immediately underneath the nipple. It runs horizontally 

 forwards, and into it all the lactiferous ducts open. The other portion of the gland 

 is very solid in character, flattened along the middle line, and in area has a length 

 of 9'50, a breadth of 3'25, and 0'25 of an inch thick. It is invested by a 

 strong fibrous capsule which is very firmly adherent to the gland substance, and is 

 with di£Q.culty removed from it.^ 



The vagina (v) has the usual Cetacean characters, and has six as tinc^e. I 

 did not observe in the vagina of the gravid female any of those remarkable glands 

 which I shall have to describe in the gravid vagina of Platanista. 



Gravid toterus. — The mouth of the true os is a Utile to one side, which also holds 

 good with the lower os tincce, thus conferring a slightly spiral arrangement on the course 

 of the canal. The true os, when viewed from the ixterine aspect (Plate XXXIII, 

 fig. 2), appears almost smooth, with only a few rudimentary folds, and in this respect 

 it materially differs from the os uteri intermmi of Flatanista (Plate XXXI, fio". 2), 

 and the Narwhal.^ In the gravid female the foetus was developed in the left horn, and 



" See Hunter, I. c. .- KuLn, Fe'russao, Bullet, des Se. Nat. 1830, t. xxii. p. 322 : Eapp, Meckel's Arcliiv. fiir. Anat. 

 1830, p. 858 : Die Cetaceen Zool. Anat. darge.stellt, 1837, p. 178 : Trail. Edinr. New Phil. .Journ. 1834, Vol. xvii. i^p. 117 

 et 363 : Is-Geoff. St. Hilaire, Ann. des So. Nat. 2 Ser. Zool. t. 1. 1834, p. 174 : Jacob, Brit. Assoc. Eeports, 1835, 

 p. 86: Astley Cooper, Anat. of Breast, 1839: H. Milne-Edwards, Lejons. sur la Physiol, t. ix, 1870, p. 124, and 

 Turner, I. c. 



- Turner : Lectures on Placent. 1876, p. 50. 



