LÖNNBERG, THE PELVIC BONES OF SOME CETACEA. 7 



known. As all rudimentary organs they are subjected to 

 great individual variations in shape and size, biit in all cases 

 they are more strongly developed and less reduced than in 

 the Southern Right Whale. The latter represents therefore 

 to a certain degree an intermediate stage with regard to 

 these organs between the Greenland Whale and the Nord- 

 caper, as it also does in other respects, for instance, with 

 regard to the length of the baleen.^ These facts tend to 

 prove the distinctness of the Southern Right Whale from 

 the Nordcaper. 



The pelvis of Balaeiioptera qiioyi (Fischer). 



Some years ago when Mr. E. Sörling was collecting for 

 this museum at South Georgia he was permitted to prepare 

 for the R. Nat. Hist. Museum, Stockholm, the skeleton of a 

 Southern Finback, measuring 19 m. 60 cm. in length, at 

 Captain C. A. Larsen's whaling factory. The pelvic bones 

 of this male specimen are shown in their general features in 

 the accompanying figure (fig. 6). 



The dimensions are the following: 



left right 



Total length without cartilages 45 cm. 43,5 cm. 



Distance from tip of ilium to lateral surface of pubis --. 35,5 » 32 » 



y> » tip of ischium to lateral surface of pubis 23 » 22 » 



Width across pubis 12,5 » 12,5 » 



The ilium is thus much longer than the ischium. Its 

 anterior part is rather strongly compressed and along the 

 lower side runs a raised crest. Before it joins pubis it is 

 becomes depressed. At the place where it is most strongly 

 compressed the transversal and vertical diametres are 20 mm. 

 and 40 mm. on the right side, 22 mm. and 35 mm. on the 

 left side. On the inner side pubis is flat on the outer surface 

 there is- an elevation which extends 6 — 7 cm. from the blunt 

 lateral tip of the bone. From the latter and över this ele- 

 vation a thin covering of cartilage is seen which according 

 to the interpretation of Struthers and other corresponds 

 to the acetabular cartilage. 



^ Conf. Lönnberg: K. Vet. Handl. Bd. 40. N:o 5 p. 42. Stockholm 

 190(3. 



