392 



DISCOVERY REPORTS 



of the total body length as against 7 per cent in the male sex. In the 2-1 m. foetus 

 dissected in the present work, the distance between the centre of the anus and the centre 

 of the vulva amounted to 5-75 cm. 



In toothed whales and the Balaenidae the anus lies within the hinder commissure of 

 the vulva and is surrounded by the same sphincter. In view of this fact some doubt may 

 be expressed whether the large fleshy lips that flank the vulva both in Mysticetes and 

 toothed whales should correctly be called the labia majora. All previous authors, 

 however, have given this name to the lips of the vulva of Balaenoptera. Anteriorly they 

 converge in front of the clitoris, to form, as stated by Beauregard and Boulart, a long 

 deep fold running forwards in the middle line (Plate III, figs. 1-3 ; Fig. 10). No sign 

 was found in the foetus dissected, nor in any adult, of any anterior rounded elevation 

 such as Turner (1870 a) found and identified with the mons veneris. 



A number of accessory grooves flank the vulva. The number and extent of these 

 grooves varies in different individuals, but two pairs of them are always present and are 

 constant in position. The mammary grooves form one of these pairs (Plate II, fig. 2; 

 Plate III, figs. 1-2; Fig. 10 d). They contain the nipples and lie close to the labia 

 majora on each side. In the 2-1 m. foetus the middle point of the mammary groove, 

 where the nipple was situated, lay opposite the clitoris, i-6 cm. from the centre of the 

 vulva. The other pair of grooves lies farther laterally (Plate III, figs. 2, 3 ; Fig. 10 e), 



one member of the pair on each side of 



the vulva. The grooves of this pair are 

 very long and exhibit an anterior deep 

 portion (Plate III, fig. 2) opposite the 

 extreme anterior termination of the labia 

 majora. In the 2-1 metre foetus the 

 centres of these anterior grooves lay 1-25 

 cm. on either side of the middle line. 

 The posterior continuations of these 

 grooves lie lateral to the nipples (in the 

 foetus 2-i m. in length the posterior 

 grooves were 2-25 cm. on either side of 

 the median line of the vulva). Between 

 these two extremities the middle portion 

 of the groove is shallow and less clearly Fig. 9. Maximum and minimum development of ac- 



visible. Other grooves are found flanking cessor y § enital g rooves in the adult female Fin whale - 

 the vulva in the adult and they vary 

 very greatly in number and position. 

 Mackintosh and Wheeler (1929, p. 58, 

 Fig. 98) give an illustration of the maximum and minimum development of the genital 

 grooves which is here reproduced (Fig. 9). In the upper illustration, which shows their 

 minimum development, it is seen that only one pair of accessory grooves is present 

 besides the mammary grooves. In the lower illustration the maximum development is 



B 



(From Mackintosh and Wheeler, 1929, Fig. 98.) 



A. Minimum development. 



B. Maximum development. 



