CHAP. IX.] 



TEETH : MARSUPIALIA. 



247 



species 90 adult skulls seen having this number of incisors and three 

 cases of abnormal number of incisors. Of these the first two must not 

 be reckoned in estimating the percentage of abnormalities in a pro- 

 miscuous sample, for Mr Thomas, who kindly shewed me these speci- 

 mens, informs me that they were preserved and brought to the Museum 

 expressly as abnormalities. The existence of these variations is never- 

 theless particularly interesting in connexion with the exceptional 

 number of incisors normal in DidKlpJtys. 



363. Didelphys marsupialis : in right upper jaw six incisors ; left 

 upper jaw and the whole lower jaw missing. B. M., 92. 11. 3. 28. 



36-t. Another specimen has on the right side |- as usual, but on the left 

 i -|. It appears that 7 1 and 7- of the two sides correspond, but on the 

 left side three very similar teeth stand in series behind p. B. M., 92. 

 11. 3. 29. 



365. D. turner! (= crassicaudata), Demerara. A single specimen of 



this species in collection. It has i 



.4 4 



44' 

 shew which of the upper incisors were missing. 



but there is no evidence to 

 B. M. 



DASYURID.E : incisors normally ~; of genera other than 

 ius, 63 normal skulls seen. 



Dasyurus sp., having only two incisors in left lower jaw; right lower jaw 

 normal, upper jaws missing [doubtful case]. B. M., 250. 



Myrmecobius fasciatus: with incisors normal 4 whole skulls, 



Right 



n 



Right 



FIG. 62. Myrmecobius fasciatus. 



I. Right and left profiles of upper jaw of No. 366. 



II. Right and left profiles of the two jaws of No. 367. 

 (Premaxillary teeth alone shewn.) 



