BEAKED WHALES, FAMILY ZIPHIID^ TRUE. 57 



triide far beyond the alveoli, only about one-ninth of their length being below 

 the superior border. They incline forward at an angle of about 45° with the longi- 

 tudinal axis of the jaw and diverge slightly at the tips. 



The teeth themselves have the same general form as those of the preceding 

 specimen, but are larger. The inner surface is flattened and the outer strongly 

 convex. The tips are quite pointed, but show some indications of wear. The 

 roots can not be seen distinctly, but appear to be closed. (PI. 22, fig. 4.) 



49599. Newport, Rhode Island. — Adult male. These teeth are longer than those 

 of the preceding specimen, and while they resemble the latter in general form, taper 

 much more gradually to the tip. The root, or portion below the point of maximum 

 girth, is much shorter than that above, and rugose, with several deep furrows. A 

 very small circular opening at the base of the root marks the orifice of the nerve. 

 The upper half of the teeth is smooth, and the tips slightly worn and fractured. 

 The small elliptical worn area is situated on the convex side of the tooth, which 

 appears to be the outer side. As the alveoli of the jaw are, however, filled with a 

 network of bone, the teeth can not be inserted in them. They were detached when 

 received. (PI. 38, figs. 10, 11 ; pi. 22, fig. 2; pi. 23, figs. 2, 3.) 



Besides the difference in the size and form of the teeth in the two sexes, it is 

 probable, as will be seen by consulting the foregoing data, that in the female the 

 apex of the teeth does not extend more than a very small distance above the alveoli 

 even in mature individuals, and probably often not more than a few millimeters; 

 while in adult males the teeth are almost entirely protruded from the alveoli, which 

 are filled with a coarse bony network. These differences are carried out in all the 

 American specimens, and also characterized the New Zealand specimens, as may be 

 learned from the accounts of Haast and Hector. 



A number of rudimentary teeth in addition to the large terminal pair have 

 been noted in the Aresquiers, Buenos Ayres, and perhaps other specimens, and 

 two such teeth were found in the mandible of the Barnegat specimen, behind the 

 large pair. One of these rudimentary teeth has been preserved. It is cylindrical 

 and moderately curved. The length is 16 mm. and the diameter 2 mm. The whole 

 tooth, with the exception of the extreme tip, is thickly coated with cement. The 

 root is closed and the crown acute and apparently abraded by use. (PI. 38, fig. 5.) 



Returning now to the question of the validity of (jrehnitzMi as a species, I would 

 say that after comparing the measurements of the Bering Island skulls with those 

 of the Atlantic coast specimens, and comparing the skulls themselves, I have been 

 unable to find any constant difference of importance, except the size and form of 

 the periotic bone. As the earbones are lacking from many of the skulls, the series 

 available for comparison is small. 



As compared with the Atlantic coast specimens, the anterior portion of the 

 periotic bone in grebnitzkii is larger, broader, and more rectangular in outline 

 when viewed from below. I observe, however, that the absolute size and outline 

 of the periotic vary considerably in the different specimens of grehmtzkii without 

 relation to age. The same appears to be true of caviivstris, but comparing the two 

 series of skulls as a whole it appears to be true that the anterior mass of the periotic 

 is larger in grehnitzkii. I do not think, however, that the latter species should be 



