444 Transactions.—Zoology. 
lar teeth, to be pointed out hereafter, I find that the lower jaw is far deeper 
in proportion to its length in the New Zealand specimen. Measured on the 
drawing of that bone on Plate 1, Vol. XXIII. of the Palsontographical 
Society of London the total length of the lower jaw of M. layardi from the 
point to angle is to the greatest depth as 8l to 1, whilst in the New Zea- 
land specimen it is as 63 to 1. In M. layardi the lower jaw is much slen- 
derer, the upper and lower border being very slightly inclined to one 
another, whereas in M. floweri the two borders form a much opener angle 
with one another, the upper border being very convex near the coronoid 
process. If both skulls were available for comparison side by side, I have 
no doubt that other differences would be detected, especially by a compara- 
tive anatomist of more experience than I possess. 
There is an important difference in the amount of curvature of the large 
tooth on each side of the lower jaw, which in the Cape specimen is so much 
arched that the apices of both teeth actually meet above the rostrum—a 
peculiarity which the late Dr. Gray thought could scarcely be a malforma- 
tion. 
In the New Zealand specimen that curvature, although existing, is not 
so pronounced, the point of the tooth standing in a vertical line above the 
centre of the root. Its form and position agree entirely with those of the 
tooth of the lower jaw brought from the Chatham Islands by Mr. H. Travers, 
and described and figured by Dr. Hector as Dolichodon (Mesoplodon) 
layardi.* Behind this mandibular tooth there is no partial hollow on the 
upper margin of the lower jaw, as if it were the cavity of an old tooth that 
had fallen out, as is the case in the Cape specimen, and which was first 
pointed out by Dr. Gray in his “Catalogue of Seals and Whales in the 
British Museum." The New Zealand specimen under review thus conforms 
also in this respect to the lower jaw obtained in the Chatham Islands. 
The anterior edge of both teeth are, however, perfectly intact, and not 
worn away like those in the Cape and Chatham Islands specimen—a pecu- 
liarity which might be traced to individual habits, and is, I suppose, not of 
any specific character. 
There is no doubt that the New Zealand and Chatham Islands speci- 
mens would open their mouth, as there is sufficient space for the rostrum to 
pass between the apices of the teeth. However, there has evidently been 
some abrasion on the inner side of both teeth, near the crown, as they are 
here somewhat worn down and polished. 
Boe o a ey 
* “Trans. N.Z. Inst.,” Vol V., p. 166, Pl. IIL., 1-5. [Gray has distinguished the New 
Zealand species as D. traversii, ‘Trans, N.Z. Inst.," Vol. VL, p. 96.—Ep.} 
