STRANDED ON THE BRITISH COASTS. 



155 



and its cranial characters agree with those regarded by True as 

 belonging to adult females. The teeth are slender, with a 

 diameter of about 13 mm.,. and were completely concealed beneath 

 the gum. Although the sex was not ascertained from observations 

 made on the entire specimen, there can be little doubt that 

 the animal was an adult female. The Cornish specimen was 

 incomplete, the part recorded measuring 15 feet in length. Its 

 teeth were uncut, and it was presumably a young male or female. 

 The other specimen, 18 ft. 2 in. long, was definitely known to 

 be of the male sex. Its teeth were large and massive, with a 

 diameter of 35-37 mm., and they projected beyond the gum. It 

 thus appeal's probable that the teeth remain uncut in the female 

 Cuvier's Whale throughout life, unless they become external in 

 old age, while in the male they are probably cut relatively 

 early. 



The coloration of this species appeal's to be variable. Certain 

 individuals have been recorded in which the upper part of the 

 head was white; and the Wexford specimen possessed this type 

 of coloration. In other cases the colour has been described as 

 dark above and light below. 



(7) Sowerby's Whale (Mesoplodon bidens Sowb.). 



This rare species is represented by three records, from Inver- 

 ness (Aug., 1915), Lincolnshire (Sept., 1916), and Wexford (Sept., 

 1914), respectively. 



The male Sowerby's Whale is provided with a pair of large 

 triangular teeth in the lower jaw, at about the middle of the 

 length of the mouth, on either side. Females have a pair of 

 similar teeth in the same position, but, so far as is known, always 

 beneath the gum. The three specimens here recorded had their 

 teeth concealed by the gum, and were presumably females. The 

 Wexford individual was, however, definitely known to be of this 

 sex. The Skegness specimen was reported to have been 18 feet in 

 length, which is unusually long for this species; and it was white 

 below — a type of coloration which has been reported by other 

 observers, although Sowerby's Whale is often completely black. A 

 list containing 33 records of this species has been given by 

 KUkenthal (1914, pp. 98, 99). 



The Ziphioid Whales are said to feed principally on Cuttlefish ; 

 and it is not impossible that the reduction of their teeth may be 

 associated with this diet. Piscivorous animals, such as the 

 Delphinidse and Crocodiles, seem to require a number of sharp 

 teeth adapted for holding their prey. In the Ziphioids, teeth of 

 this character are obviously not required ; and it may be suggested 

 that the absence of teeth is an advantage to them, since the 

 suckers of the Cuttlefish would probably attach themselves to 

 such convenient pegs, were these present, and the operation of 

 swallowing the prey might thus be rendered more difficult. It 

 must not be forgotten, however, that the Sperm Whale, which is 



