383 DISCOVERY REPORTS 



whales the tag was observed in 14 (6-8 per cent). Not all these whales were examined 

 for this structure, but it was definitely not present in 40 immature Fin whales. 



Of 36 female Fin whale foetuses 5(14 per cent) possessed the band while 2 definitely 

 did not. Again in some cases observations could not be made. 



There is some evidence that this peculiarity is not hereditary. In Fin whales Nos. 173 

 and 289 vaginal bands occurred in the foetuses but there was no sign of a tag in the 

 adults. The broken ends, however, may possibly have been reabsorbed so far as to be 

 inconspicuous. In Nos. 286 and 332 there was a tag in each of the parent whales 

 and no band in either of the foetuses. One foetus, however, was very rotten and it is 

 just possible that a band may have been missed. 



Whale No. 1494, a Blue female, possessed a tag attached anteriorly. This was the only 

 case where evidence of the vaginal band was found in any species other than Fin whales. 



The presence of an unbroken vaginal band usually denotes sexual immaturity, for 

 it is difficult to see how coition could occur without rupture of the band, and coition 

 probably occurs quite shortly after the female becomes adult. In this way it appears 

 to be somewhat analogous to the hymen in the human subject. 



There are two cases, however, of vaginal bands occurring in whales, one of which 

 appeared to be on the threshold of maturity, and the other just passed maturity. In 

 the former, whale No. 139, one of the ovaries showed a large vesicle 6-5 cm. in diameter 

 which was apparently an enlarged Graafian follicle. The ovaries appeared otherwise 

 to be immature. They were small, weighed comparatively little (8 and 13 oz.) and 

 the other follicles present were minute. The whale was smaller than the smallest 

 certainly mature female Fin whale, and it was captured at the end of March. Whale 

 No. 76 appeared to have just reached maturity, for it measured 20-2 m. (the mean size at 

 which maturity is reached is 20-0 m. in female Fin whales) and although a vaginal band 

 was present a body was found in the ovaries which appeared to be an old corpus luteum. 

 In this whale, which is referred to again on a later page, either an ovulation had taken 

 place or an ovum had ripened and become atretic. The second possibility is the more 

 likely as no path could be traced from the capsule to the exterior of the corpus luteum. 



The vaginal band appears not to have been previously described, and it is difficult 

 at present to put forward any explanation of its occurrence. It has been found 

 in too large a percentage of Fin whales to be dismissed as an abnormality, yet no 

 correlation has been noticed with the measurements or other features of these whales 

 to distinguish them from whales in which the band is absent. 



THE OVARIES 



The ovaries are, from our point of view, the most important of the reproductive 

 organs, for they are an unfailing index of the sexual condition, and to some extent of 

 the sexual history of the whale. They are elongated bodies measuring usually between 

 20 and 40 cm., and differ from the ovaries of most other mammals in their highly 

 convoluted condition and the prominence of the frequently numerous corpora lutea 

 and follicles, which give the surface a very irregular appearance. 



