54 ODOB^NUS ROSMARUS - ATLANTIC WALRUS. 



ers. The young animal has five upper molariform teeth (" Baek- 

 zahne"), the last two of which are smallest and early disappear, 

 and also later the third, leaving only two behind the canine, 

 and an anterior molariform incisor. In the lower jaw there are 

 only four "Backzahne" on each side, of which the last and 

 smallest very soon falls away. The dental formula given is as 

 follows: (|j=) + J + (=|) = temporary dentition: 1. 1=|, 0. 

 fEi> M - Ei5 adult dentition: I. i=, C. i=-J, M. 5|. While 

 Giebel accepts the first permanent tooth of the molariform series 

 of the upper jaw as an incisor, and the first, in the lower jaw as 

 a canine, he recognizes only two persistent molars on each side, 

 above and below. 



Malmgren,* in 1864, figured the dentition from a foetal speci- 

 men, and published an elaborate paper on the dentition of the 

 Walrus, in which he reviewed at some length the history of the 

 subject, noticing quite fully the writings of the early authors, 

 from Crantz to the Cuviers, and the papers of Bapp, Owen, 

 Wiegmann, Mlsson, and other later writers. The formula he 

 presents as that of the permanent dentition is : I. J-^J, C. ~^ 7 

 M. jJ5f=^=18; and for the deciduous dentition: I. |=|, C. J-=, 



The specimen figured shows both the permanent and decidu- 

 ous dentition. The deciduous teeth are most of them separately 

 figured, of natural size, as minute, slender, spindle-rooted teeth, 

 with short, thickened crowns. The permanent teeth are already 

 in place, although even the upper canines had probably not 

 pierced the gum. The middle pair of incisors of both jaws had 

 already disappeared, leaving only their distinctly recognizable 

 alveoli. His specimen appears to have had but a single cadu- 

 cous molar behind the permanent series, from which he assumes 

 the number of upper molars to be 4 4 instead of 5 5. 



The following year, Peters J referred to Malmgren's paper, 

 publishing a plate illustrating the dentition as existing in a some- 

 what older skull (received from Labrador) than that figured by 

 Malmgren. Peters here takes exception to Mahngren's assumed 

 number of back-teeth, which, in accordance with the views of Eapp 

 and Wiegmann, Peters believed should be |^|, instead of ^~. 



* Ofversigt af Kongl. Vet.-Akad. FSrhaiull., 1863, pp. 505-522, pi. vii. 

 t The paper being published in Swedish, I am unable to follow him in his 

 discussion of the subject. 

 t Monatsb. K. P. Akad., 1865, pp. 685-687, pi. facing p. 685. 



