I20 DISCOVERY REPORTS 



The pigmentation of the foetus, darker above and Ughter below, and the persistence 

 of Ught ventral patches in some adults points to the descent of the Sperm whale from 

 ancestors of the more usual dolphin pattern of coloration. 



BODY SURFACE, PALATE AND TONGUE 



The body surface of the adult Sperm whale does not present the smooth appearance 

 found in the Fin whales. On the back, and on the flanks between the flippers and the 

 tail flukes, a corrugated appearance is presented which may be more or less developed 

 (Plate VI, fig. 3). The corrugations are formed by a number of shallow ridges, some 

 15 cm. apart, running fore and aft, and when well developed produce a very irregular 

 surface to the body. On the ventral surface the corrugations are frequently strongly 

 developed as three or four ridges which have their greatest height below the insertion 

 of the flippers and extend from a short distance posterior to the jaw to the region of the 

 umbilicus (Plate VII, fig. i ; Plate IX, fig. i). The ridges are irregular in shape and may 

 give off branches and anastomose. The corrugations are present also on the outer sur- 

 faces of the flippers and produce an appearance as of the bones of the digits causing 

 projections on the surface, though dissection shows that the ridges do not necessarily 

 occur over the bones. 



The dorsal fin is small and hump-like, so that it is difficult to determine its anterior 

 and posterior borders, while between it and the tail flukes a number of lesser humps and 

 corrugations are present, the ridge of the tail thus showing an irregular outline in 

 profile (Plate VI, fig. 3). The lesser humps are usually four or five in number and 15- 

 20 cm. in height. On the ventral surface just behind the anus a rather larger hump is of 

 constant occurrence (Plate VI, fig. 2; Plate IX, fig. 2). 



Below the angle of the gape a groove is present on each side of the lower jaw, running 

 a short way on to the throat (Plate X, fig. i). These throat grooves are not very pro- 

 minent and may be supplemented by three or four smaller grooves on each side, while 

 a median groove as large or larger than the paired throat grooves may be present between, 

 and a little posterior to, the paired grooves. The grooves are represented in the foetus of 

 3-0 m. in length by twelve to fifteen shallow irregular grooves on the throat (Plate IX, 

 fig. i). In addition a pair of transverse grooves may be present running for about i m. 

 outwards at the posterior termination of the longitudinal grooves. There are nine 

 records, eight positive and one negative, of the transverse throat grooves in the 

 observations. 



The palate and upper surface of the tongue of the Sperm whale are very light grey, 

 almost white (Plate VIII, fig. 2). The under surface of the tongue is usually pink, but 

 occasionally a shade of grey slightly darker than the upper surface. In four whales small 

 patches of dark pigment were observed on the palate. 



TEETH 

 The lower jaw of the Sperm whale carries from twenty to thirty teeth on each side, 

 the number on each side not necessarily being equal (Plate VIII, fig. 2; Plate IX, fig. 3 ; 

 Plate X, fig. i). When the mouth is closed the tips of the teeth fit into sockets in the 



