MILK-DENTITION. 481 



Jersey, in beds of Cretaceous age. Aii error of horizon, if not 

 of locality, being admitted in case of the last named, it appears 

 thus far that no traces of Pinnipeds have been met with in beds 

 older than Miocene. 



MILK-DENTITION. 



Iii the Phocidw, as in the other Pinnipedia, the milk-teeth are 

 very small, are perfectly functiouless, and persist for only a 

 short period beyond foetal life. As in the other Carnivores, 

 the number of milk-teeth in the molar series is three, and their 

 position is the same as that of the deciduous molars of the 

 fissipede Ferce, standing respectively over the second, third, 

 and fourth of the permanent set. The incisors and canines are 

 each preceded by deciduous teeth, always minute, and generally 

 absorbed prior to the birth of the animal, as are also, in most 

 cases, the deciduous molars. It is consequently difficult to 

 obtain dry specimens that retain the minute milk-teeth, they 

 being usually partly or wholly (especially the very small in- 

 cisors) lost in the preparation of the specimen, or by subsequent 

 handling. Alcoholic or fresh specimens alone afford satisfac- 

 tory material, and these are not often accessible. The milk- 

 dentition of most of the northern genera of Phocids has, how- 

 ever, been described, but I have met with no reference to that 

 of any of the genera of the Stenorhynchinw. As already stated, 

 each incisor of the permanent dentition is preceded by a milk- 

 tooth, and the number of temporary incisors thus varies in the 

 different genera in accordance with the number of permanent 

 ones. The Sienorhyncliime will doubtless be found to afford no 

 exception as regards the relative number and position of the 

 deciduous teeth. 



Steenstrup, * in 1861, described and figured the milk-dentition 

 of Erignafhus barbatus and Phoca grcenlandica, and described 

 also that of Phoca frjetida. Kordmann, t at about the same 

 date, described that of Halichcerus, and in 18G5 the milk-denti- 

 tion of Cystophora cristata was described and figured by Rein- 



* Maelketandsaettet hos Kemmesselen, Svartsiden og Fjordsaelen (Phoca 

 barbata 0. Fabr., Ph. yronlandica O. Fabr., og Ph. hispida Schreb.), og i An- 

 leduing deraf nogle Bemserkninger om Tandsystemet hos to fossile Slaegter 

 (Hycenodon og Pterodon). Af Professor Japetns Steenstrup. Vid. Medd. fra 

 den naturh. Forening i Kjobhavn, 1860 (1861), pp. 251-264, pi. v. 



t " Palaeontologie Siidrusslands, ivAbth. vorgetr. in d. Finnl. Soc. d. Wiss., 

 1860, pp. 306-308.1' The only copy of Nordinaun's work accessible to me is 

 imperfect and unfortunately lacks the iv Abth. 

 Misc. Pub. No. 12 31 



