54 ODOB^NUS EOSMAEUS ATLANTIC WALEUS. 



ers. The young animal has five npx)er molariform teeth (" Back- 

 zahue"), the last two of which are smallest and early disapi^ear, 

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

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

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

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



foUows:"(|5j) + I + (^)" = temporary dentition : I. |e|, 0. 

 fei, M. 1=1; adult dentition : I. ^, C. i^-J, M. '?. AYhile 

 Giehel accepts the first jiermanent 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 pubhshed 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 Eapp, Owen, 

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



presents as that of the permanent dentition is : I. q-^, C. ^j 

 M. |^=j=18; and for the deciduous dentition: 1. 1^, C. ^-^, 

 M. t^^=i^=32. t 



4 4 Id 



The specuuen 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 abeady 

 in place, although even the upi)er canines had probably not 

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

 already disappeared, leading only then- distinctly recognizable 

 alveoh. His specunen 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 | 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 IMalmgren's assumed 

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

 and Wiegmann, Peters believed should be |5|, instead of J^^. 



* Ofversigt af Kougl. Vet.-Akad. Forliaudl., 1^63, pp. 505-522, pi. vii. 

 t Tlie paper being xmblislied iu Swedish, I am unable to follow Mm in bis 

 discussion of tbe subject. 

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



