BEAKED WHALES, FAMILY ZIPHIID^ — TRUE. 7 



however, that in the Overstiand, Enghmd, specimen (1S92), which was an adult 

 female, the teeth did not project beyond the gums. Messrs. Southwell and Ilarmer 

 say regarding it : 



The jaws were apparently completely edentulous, and although it was possible to feci through the 

 gums a slight prominence on either .side in the position of the teeth of the male, we could not by this 

 means definitely satisfy ourselves with respect to this point, nor were we able to ascertain the presence 

 of any other rudimentary teeth in either jaw. The evidence which exists on this subject is favourable 

 to the \iew that the female of this species is not provided with any teeth which are large enough to 

 pierce the gums." 



It is probable that the teeth in tlie Xantiuket specimen, though (luite large, 

 did not project beyond the gums any considerable distance. The external border 

 of the alveolar groove behind the tooth is only 20 mm. below the apex of the tooth, 

 and it is not unlikely that the gums in a specimen of this size had nearly that tluck- 

 ness, so that only the tip of the tooth would project beyond them. Though the 

 apex is acute, it has a flat abraded surface anteriorly, which, however, is but 4 mm. 

 long. It seems probable, on the whole, that the teeth in the female may be quite 

 large without projecting more than a few millimeters beyond the gums. 



In shape the tooth of the Nantucket specimen is almost identical with that of 

 Sowerby's Brodie House adult male, as figured by Lankester. The dentine at the 

 apex is more nearly white than the cement which surrounds it. The superior 

 margin of the latter is not a plain ring, but sends upward a papilliform projection 

 on each side. The dentine itself has two vertical grooves on each side. The root 

 of the tooth ends very obliquely and is rugose and irregular. The cavity is closed. 



Grieg remarks as follows regarding the structure of the teeth of the Rugsund 

 specimen: 



Sections and microscopic preparations of the alveolar tooth of this whale show that its apex consists 

 of dentine, within which is found an inner pulp cavity 4 mm. long and 1 mm. broad. The dentine, 

 the structure of which agrees with that which Turner found in Mesoplodon bidens and Mesoplodon layardi, 

 is yellowish white, with the exception of the part nearest the pulp cavity, which is yellowish brown. It 

 seems to correspond most closely to what Ray Lankester called osteodentine. Throughout the tooth the 

 dentrine is covered with a very thin layer of shining white enamel. The enamel is. however, lacking on 

 the front of the tooth, having probably been worn away. A section through the middle of the tooth, at 

 right angles with the V-shaped furrow, shows a yellowish cement layer from 3 to 5 mm. broad, which is, 

 however, worn away on the front of the tooth. Within the cement layer is a white, amorphous, calcareous 

 mass, forming a band from L.5 to 3. -5 mm. broad, which appears to correspond to Ray Lankest^r's "glob- 

 ular matter" and Turner's "modified vasodentine." The mass seems to agree most closely with Ray 

 Lankester's "globular matter," as it has "no structure excepting an indistinct botryoidal character visi- 

 ble with a low magnifying power." The core of the tooth consists of dentine, the inner layer of which 

 is brownish, while the outer is rather whitish yellow. As above mentioned, the dentine is visible on 

 the front of the tooth, since both the cement and the amorphous, calcareous mass are w^orn away. More- 

 over, it is clear that on the front of the tooth the dentine is not covered by enamel. The pulp cavity is 

 reduced to a fine pore. A section across the root of the tooth shows an outer yellowish cement layer, 

 from 2 to 5 mm. broad, while the interior of the tooth is filled with a white, amorphous, calcareous mass, 

 which is interspersed with thin yellowish lamellae of dentine. Here and there, also, thin lamellje are 

 seen to extend from the outer cement layer into the white, amorphous, calcareous mass. The dentine 

 lamellse appear to be identical with what Ray Lankester calls osteodentine. No pulp cavity is visible 

 in the root of the tooth.* 



o Ann. and Mag. Nat. Hist., ser. 6, vol. 11, 1893, p. 277. 

 ftBergena Mus. Aarb., 1904, No. 3, pp. 27,28. 



