| OCR Text |
Show 480 DR. J. V. HAAST ON MESOPLODON FLOWERI. ("June 6, Measured on the drawing of that bone in the figure given by Prof. Owen, the total length of the lower jaw of M. layardi, from the point to the angle, is to the greatest depth as 8^ to 1, whilst in the New- Zealand specimen it is as 6\ to 1. In M. layardi the lower jaw is much more slender, the upper and lower border being very slightly inclined to one another, whereas in M. floweri the two borders form a much more open 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 comparative anatomist of more experience than I possess. There is an important difference in 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 malformation. 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 a lower jaw brought from the Chatham Islands by Mr. H . Travers, and described and figured by Dr. Hector as Dolichodon (Mesoplodon) layardi in the fifth volume of the 'Transactions of the New-Zealand Institute.' 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 edges of both teeth, however, are perfectly intact, and not worn away like those in the Cape and Chatham Island specimens; a peculiarity which might be traced to individual habits, and is, I suppose, not of any specific value. There is no doubt that the New-Zealand and Chatham-Island specimens couldopen their mouths, 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. The small enamelled portion rising on the anterior edge of the apex is not quite so large as in the Cape specimen. The lower jaw from the Chatham Islands is 1*75 inch shorter than that of the specimen under review, in which latter the mandibular tooth is also much longer, which may be regarded as an individual difference only. The following Table of measurements will also supply further material for comparison :- Dimensions of the skull. ft. in. Extreme length of cranium 3 5*75 Length of rostrum from the apex of the prae- |
