621 



Recently Freund 6 ) in a paper on the development of the Rodents' 

 dentition has redescribed these vestigial incisors and ascribes their 

 discovery to Pouchet and Chabry, he describes their development 

 and the relation of their enamel organs in detail. Whilst giving it 

 as his opinion that these minute teeth are in all probability the milk 

 predecessors of the large incisors, states that he does not think it can 

 be absolutely proven as yet. 



Simultaneously with Freund's paper I published one on the same 

 subject in which I pointed out that Huxley was the original dis- 

 coverer of these teeth and adopted his view as to their homology 

 viz: — that they represent the last vestigies of the milk precursors of 

 the large incisors. (Proc. Zool. Soc, 1892, pp. 38 — 49.) 



Freund has also discovered traces of the rudimentary milk in- 

 cisors in the Squirrel both above and below, and also two tooth rudi- 

 ments close to Stenson's canal one of which he regards as an incisor 

 and the other as a canine. 



The latest observations on this interesting subject are those of 

 Noack 7 ), he describes the tooth development in various stages of 

 Lepus vulgaris (Europaeus or timidus) and also in C u n i - 

 cuius ferus (Lepus cunicul us) 8 ); in the latter he describes in 

 an embryo with head length 21 mm the presence of a canine and a 

 possible trace of a posterior incisor. 



Unfortunately he does not figure any of these highly interesting 

 discoveries neither does he state as to whether these dental rudiments 

 were calcified or not, and whether they were micro- or macroscopic. 



He further gives a most fanciful series of milk dentitions for a 

 number of genera of Rodents based solely on the presence of minute 

 pits which he has discovered in the jaws of the animals. The validity 

 of these discoveries and his assertions that the three incisors present 

 in the young Rabbit are all to be refered to the permanent dentition 

 I shall deal with at the end of this paper. 



6) P. Fbetjnd, Beiträge z. Entwickelung d. Zahnanlagen b. Nage- 

 thieren. Archiv f. mikr. Anat., Bd. 39, 1892, p. 525. 



7) T. Noack, Neue Beiträge zur Kenntnis der Säugetier-Fauna von 

 Ostafrika. Zool. Jahrb., Abth. f. System., Bd. 17, H. 4, 1893, p. 523 — 594. 



8) Noack's nomenclature is very confusing, for however advisable 

 it may be to subdivide the genus Lepus into two yet the revival of 

 the generic name Cuniculus for the Babbit, although originally so 

 applied by Pliny, is very questionable, as it has since been used by Wagi.ee 

 in 1832 for the Arctic Lemming (Cuniculus torquatus) and is 

 generally adopted for that animal by subsequent writers. 



