TURSIOPS TURSIO. 37 



Dr. Fiscbei's Nos. 8 mid 1), of iiukiiowii sex, but which from a coii.sid 

 eratioii of the proportions ho believes to be females, should, I think, be 

 regarded as males if the length of the mandible alone is considered, but,. 

 on the contrary, as females if the breadth of the beak is considered. 



From the facts presented, and numerous others, I am inclined to re- 

 gard the variation in cranial proportions as of little value in determin- 

 ing the sex. From Dr. Fischer's material and that to which I have had 

 access, however, we arc able to get some idea of the limits of variation 

 in cranial proportions. Tlie greatest and least proportions, as regnrds 

 the length of the beak in thirty-five specimens, are as follows : 



Proportion of length of beak to total length of skull: 



Greatest 58.2 per cent. (Dr. Fischer, No. 1, J' tres adultc). 



Least 52.9 per cent. (11997, Fort Macon, young). 



[Note 48.7 per cent, in foetus, 24300, Hatteras. J 



Proportion of width of beak at base to its length : 



Greatest 51. 9 i)er cent. (Dr. Fischer, No. 4, 9, cpiph.). 



Least 41.5 per cent. (22080, Hatteras, not old). 



[Note 48. 7 per cent, in ftetns, 24300, Hatteras.] 



Proportion of \Yidth of beak at middle to its length : 



Greatest 3G. 7 per cent. (Dr. Fischer, No. 11, 9, opipb.). 



Least 24. 8 per cent. (22080, Hatteras). 



[Note 31. G per cent, in foetus, 24300, Hatteras. ] 



The skull absolutely longest of this series is Dr. Fischer's N'o. 1, a 

 male "tres adulte," 55<"' ; my largest specimen is No. 22304, old female, 



52.9'^>". 



Tiirsio curynome Gray. 



I pass now to the consideration of the species identical with or allied 

 to T. iursio. The first of these is T. eiirynome, Gray, founded on a 

 single skull, No, 35Gfr, in the British Museum. The chief characters 

 which Gray gives are cranial proportions. Eegardiug its relation- 

 ships he says : 



Tbo skull of this species is most like D. Uirsio ; but the nose is one-fourth lougcr 

 than the length of the head, slenderer and more rounded, and the teeth smaller.* 



In the diagnosis of i>. /«mo, however, he has: "Skull-nose five- 

 ninths the entire length." On comparing his measurements of T. eiiry- 

 nome, it appears that this proportion exists here also. In relative 

 breadth the beak exceeds several of the North Carolina skulls, notably 

 No. 22304, 9 , from Hatteras, which is only 3""" larger. It agrees very 

 closely in absolute size of parts with Dr. Fischer's $ No, 1. In none 

 of its relative proportions does it fall outside the limits of variation of 

 the series discussed on page 35. Speaking of this skull and others in the 

 series. Gray himself says: "These are all very much alike." t Professor 

 Flower includes it in his "section " T. iursio, with others, saying that 



*Cat. Seals and Whales, p. 2ol 

 tSuppl. Cat. Seals and Whales, p. 75. 



