72 BULLETIN 73, UNITED STATES NATIONAL MUSEUM. 



backward. The root is very unsymmetrical, the posterior portion being much 

 longer than the anterior. The surface is very rugose, and there is no opening what- 

 ever below. The inferior border is convex, ^vitll an emargination near the center. 

 (Pi. 39, figs. 7, 8.) 



In the adult skull from Beiing Island, which has been mounted and placed on 

 exliibition, the teeth are fixed in the alveoli so that their entire length and the pecul- 

 iarities of the basal portion can not be determmed. In general form, however, 

 the}' resemble those of the preceding specimen very closely. The anterior teeth 

 are placed ol^liquely — that is, so that the anterior margins of the two teeth arc 

 nearer together than tlie posterior margins. The teeth are also somewhat inclined 

 forward. The posterior teeth are strongly inclined forward and a little outward. 



The anterior teeth are rather concave along the middle internally and convex 

 externally. The portion above the alveoli is quite smooth. 



The posterior teeth are moderately rugose above the alveoli. The wlutish tips 

 of denture are conical, compressed, and rather acute. They extend 6 mm. above 

 the denture, and are 11 mm. long at their l)ase, and 6 mm. thick. 



The anterior teeth protrude about 4.5 mm. above the alveolus (internally) ; 

 their base at the alveolus is from 73 to 76 mm. long, and from 33 to 3.5 mm. thick. 

 The posterior teeth extend about IS mm. above the alveoli (measured vertically 

 from the alveolus), and the base of the visible portion (measured along the alveolus) 

 is from 30 to 34 mm. long and from IS to 20 mm. tlnck. These teeth have an antero- 

 external angular enlargement of the cement, so that they are somewhat triangular 

 in horizontal section. (PI. 30, fig. 3; pi. 31, fig. 5.) 



The data available are insufiicient to enable one to determine satisfactorily 

 whether the teeth dift'er materially in size in the two sexes, but it appears probable 

 that they do not. 



SKELETON. 



While the skeleton of Berardius bairclii (PI. 42, fig. 4) resembles that of B. 

 arnuxii very closely in most particulars, it presents differences which may properly 

 be regarded as specific. The vertebral formula of B. arnuxii as given by Flower is 

 as follows: C. 7, Th. 10, L. 12, Ca. 19 = 48." The same formula is given for another 

 specimen of B. arnuxii by Van Beneden and Gervais, except that the caudals are 

 17, two being apparently lacking.* 



Doctor Hector, however, gives a difi'erent formula for a third specimen of this 

 species, namely, C. 7, Th. 10, L. 13, Ca. 17 = 47. He remarks that "extreme care 

 was taken to secure the whole of the small tail bones."'' The discrepancy here 

 shoMm can not be accounted for at present, but, at all events, none of the formulas 

 of B. arnuxii corresponds to tliat of B. hairdii, as derived from the three skeletons 

 in the National Museum, namely, C. 7, Th. 11, L. 12, Ca. 16+ =46+ . 



The number of thoracic vertebriB can be determined positively from the youngish 

 male from St. George Island (Cat. No. 49727), in which ten pairs of ribs are present, 

 together with one rib belonging to the eleventh pair. This last is much shorter 



a Trans. Zool. Soc. London, vol. 8, 1872, p. 223. 



6 Ost^ographie des Cetaces, p. 615, pi. 23 Ws. 



c Trans. New Zealand Inst., vol. 10, 1878, p. 339. 



