16 



BULLETIN 36, UNITED STATES NATIONAL MUSEUM. 



existence in S. leniiginosa of (1) a relatively longer beak, (2) flatter 

 interinaxillai (3) a longer tooth-row, and (4) more numerous teetli, I find 



(5) that the symphysis of the mandible is longer than in 8. gadainu, 



(6) the temporal fossae are larger, (7) the pterygoids are longer, and (8) 

 the interorbital breadth less (see table of measurements below). The 

 whole relative arrangement of the bones of the inferior surface of the 

 skull differs in the two species. 



In regard to external appearance, if the figures published by Sir 

 Kichard Owen are to be relied ujion, the two species, 8. leniiginosa and 

 S.gadamu, are very different (T. Z. S., vi, 1866, pi, 3 {8. gadamu), pi. 5, 

 figs. 2, 3 {8. lentiginosa). In addition to the difference in color and 

 style of marking, the proportions of the pectoral tin, as presented both 

 by the measurements and in the plates, are such as would alone suffice 

 for the separation of the two species. The length of this member in 8. 

 gadmnu is fully 22 per cent, of the entire length of the animal, while in 

 8. lentiginosa the former length is less than 13 per cent, of the latter. 

 Differences of almost equal magnitude exist in the proportions and rela- 

 tive positions of other members of the body. The value of these dis- 

 tinctions, however, would be greatly enhanced if we could be sure that 

 the measurements were derived from the specimens themselves and not 

 from the drawings. LTnfortunately the intimation derived from the first 

 paragraph of Sir Richard Owen's paper is that they were derived from 

 the drawings. Even should such prove to be the case, the differences in 

 the skulls remain, and these alone, in my estimation, are sufficient to 

 warrant the separation of the species. 



Mtmurements of the type skull of Sotalia lentiginosa. 



*Thi3 is the extent of the roupise area; the ro;il symphysis is about 5.3 cm. 



