840 "Transactions.— Zoology. 
able to give a figure (plate XVII.) from a photograph which I had taken by 
permission of Prof. Hutton. The other group, of which the type of M. 
hectori is an extreme though very young example, represents the forms 
similar to M. europæus of the northern seas. 
These extreme forms are separated, but with many intermediate examples, 
chiefly on account of the position and size of the tooth in the mandible, a 
character to which I think too much importance has been attached, as no 
two specimens yet obtained agree perfectly in this respect. 
The complete skeleton of an adult male of M. hectori which I obtained 
in Lyall Bay, near Wellington, in January, 1875,* agreed perfectly with. 
those parts which had been preserved by the late Dr. Knox of the type of 
the species from Tetai Bay, Porirua Harbour, but in this second case the 
teeth were situated several inches from the tip of the mandible, while in the 
type they were at the extreme tip, though still lateral and not terminal as 
in Ziphius.} 
Again, in the very young specimen of which I obtained only the lower 
jaw from Kaikoura, the teeth were opposite the hinder edge of the 
symphysis. } 
Dr. von Haast has lately described under a new genus Oulodon§ three 
specimens obtained by Mr. Hood in the Chatham Islands of a Mesoplodon, 
which has a row of small teeth in the upper jaw, in a position corres- 
ponding to the shallow emargination of the upper part of the ramus of the 
mandible of the Otago Museum skull (a. fig. 1, pl. XVII). No anatomical 
description of Oulodon has yet been published, and as the characters of the 
skulls figured and deseribed by Dr. von Haast were concealed by the dried 
integument, its exact affinity to the other species of Mesoplodon cannot be 
detected ; but, while the longest of the skulls (No. 1) has the mandible 
produced to three times the width between the articulations (computed from 
the orbital width which is given by Dr. von Haast) and the teeth atone- 
third the length of the mandible from the tip, in both of which characters 
it again agrees with the Otago Museum skull, the shorter skull (No. 3) has 
the length of the mandible only twice the articular width, and the tooth at 
one-fourth the length of the mandible from the tip, thus approaching M. 
hectori in its proportions. 
The presence of rudimentary teeth in the upper jaw of Mesoplodon is 
certainly a most interesting discovery, but the animals have so seldom been 
examined in the flesh that it may not prove to be of uncommon occurrence, 
although it bas escaped the notice of all naturalists prior to Dr. von Haast. 
— —. * Trans. N.Z. Inst., VIL, 262. 
{ Trans. N.Z. Inst., VI., pl. 15a. 
t Trans. N.Z. Inst., IT., pl. 14, 15. 
§ Trans. N.Z. Inst., IX., Art. LVI. 
