TURSIOPS TURSIO. 



33 



collection. This series comprises about forty-five specimens, of whicli 

 ten are fragmentary, and three fcetal or very young. Of four only is the 

 sex known. 



The greater part of these skulls were collected by Dr. II. C. Yarrow 

 at Fort Macon, North Carolina; others are from the fishing grounds at 

 Hatteras, Nor';!! Carolina; and the remainder arc from different jjoints 

 on the Atlantic coast between New Jersey and Florida. The species 

 is perfectly well known to our fishermen. Large numbers have been 

 taken for many years at Hatteras, where I have myself witnessed the 

 capture of between eighty and ninety in a single day. These individuals 

 were about equally divided between the two sexes, and were of all ages. 



From the skulls above mentioned I have selected twenty-one perfect 

 specimens of nearly equal size for comparison. Their sex is unknown, 

 but from the fact that they were picked uj) at random on the beach, and 

 that males and females frequent this coast in about equal numbers, it 

 is highly improbable that all are males or all females. If there are 

 diii'erences between the sexes as regards the proportions of the length 

 and width of the beak they should appear on comparison of the meas- 

 urements. 



In his valuable paper on the cetaceans of Southwestern France, Dr. 

 Fischer calls attention to sexual differences in the skulls of Tursiops 

 tiirsio. His words (translated) are as follows:* 



Upon examining together the heads of males and females, one per- 

 ceives that they present characteristic differences. The beak is longer 

 and relatively narrow in the males. * * * The heads of the females 

 are remarkable on account of the breadth of the beak at its base and 

 at the middle; the beak has consequently a more triangular form. 



The measurements given by Dr. Fischer do not entirely bear out these 

 statements. From these the following results are obtained; 



It appears from these comparisons that $ 1 has a longer and nar- 

 rower beak than 9 0; (5 3 has a s/<orfe/' and narrower beak than 9 I 

 9 11; and S 7 has a longer and wider beak than 9 5. Thus we have 

 three of the four possible combinations — long and narrow, long and 

 wide, short and narrow— in the same sex. 



*Actes lie la Soc. Linn, dc IJurileaux, 4""' s6r., v, 1881, p. 159. 



18378— Bull. 30 3 



