38 



DISCOVERY REPORTS 



seven, the latter from whale no. 2000, which must have been an exceptionally hairy 

 whale, for the hairs on the chin and mandibles were also above the average in number. 

 The hairs on the chin are arranged in two groups, one at the tip of the jaw and the 

 other paired, on a group of tubercles a short distance below the first. The hairs in the 

 median group, which may be up to 2-5 cm. long, are usually arranged irregularly. 



Table XI. Humpback whales. Occurrence of hair 



though sometimes in three or four lines, and number from twelve to forty. The hairs in 



the lateral groups on each side of the median line are rooted in tubercles and number 



from four to five on each side. The mandibular hairs are placed on tubercles arranged 



along the ramus of the jaw, and number from two to eleven on each side. 



It will be noted from the above description that there is considerable individual 



variation in the number of hairs present, the arrangement of which appears to differ in 



no way from those of the northern Humpback whales, as described by True (1904) and 



others. 



VENTRAL GROOVES 



The ventral grooves are spaced proportionately very much farther apart in the 

 Humpback than in the other Balaenopteridae and consequently are fewer in number. 

 The average of nine counts, excluding the short grooves at the insertion of the flippers, 

 in the present series is twenty-eight, maximum thirty-six, minimum twenty-one. These 

 may be compared with the corresponding figures (Mackintosh and Wheeler, 1929) for 

 Blue whales, average ninety, maximum one hundred and eighteen, minimum seventy, 

 and Fin whales, average eighty-four, maximum one hundred and six, minimum sixty- 

 eight. The numbers of ventral grooves found in the present series are shown in 

 Table XII. 



Lillie (191 5) records the grooves in the New Zealand Humpback as "about twenty- 

 four" between the flippers. On the other hand Millais (1906) gives the number of 

 grooves as eighteen to twenty-six in the northern Humpback, but does not state how 

 many specimens were examined to arrive at this figure. The present data average above 



