LÖNNBERG, THE PELVIC BONES OF SOME CETACEA. 9 



On the whole these rudiments of pelvis and femur of 

 Balcenojotera quoyi resemble the corresponding ones of its Nor- 

 thern relative Balcenoptera physalus, which are subjected to a 

 considerable variation in some respects as is shown in Abel's 

 memoir ^ in which he has quoted Struther's and other authors 

 and reproduced their figures in addition to the results of his 

 own investigations. 



The attachment of the femur rudiment in the Southern 

 Fin Whale agrees also with Struther's observations on the 

 Northern species.^ 



The pelyic rudiment of Balaeiioptera iiitermedia 



Burmeister. 



Through the courtesy of Captain C. A. Larsen the R. 

 Nat. Hist. Museum has obtained a complete skeleton of an 

 adult but not very old Southern Blue Whale from the seas 

 round South Georgia, and I have thus the opportunity of 

 describing the pelvic rudiment of this interesting animal. 



The pelvic bone of this species is much more rcduced 

 than that of its ally Balcenoptera quoyi. It consists of a 

 triangulär bony plate with cartilaginous epiphyses as w^ell at 

 the end of the ilium as that of the ischium. The whole is 

 enclosed in a capsule of fibrous tissue as the figure (fig. 7) 

 shows The length of the bony parts is about 195 mm., and 

 the width across the bone is about 110 mm. The pubic 

 portion is thus when compared with the size of the whole 

 rudiment considerably more strongly developed than in B. 

 quoyi while the other elements are shorter. The cartilage 

 which may be interpreted as belonging to the ilium is rather 

 short and slender measuring about 30 mm. in length. The 

 cartilage of the ischium is broader and much longer, about 

 115 mm. 



The whole bone is thin. The thickest part of the pubic 

 portion has a diameter of about 28 mm., otherwise the grea- 

 ter part of the whole bone is 17—13 mm., and mesially it 

 narrows gradually to a rather sharp edge. The whole bone 

 is of a porous and loose texture. There was no rudiment 



^ Hiiftbeinrudimente der Cetaceen. 



2 Journ. Anat. Physiol. Vol. XXVII. London 1893. 



