MAY, 1921. AMERICAN MARSUPIAL, C^NOLESTES OSGOOD. in 



7. Sagittal and lambdoid crests absent. 



8. Postorbital processes absent. 



9. Paroccipital and mastoid processes small and prostrate. 



10. Lacrymal canal with a single opening. 



11. Postzygomatic foramen lacking. 



1 2 . Stapes colurnellif orm. 



The first five of these characters are exclusive resemblances to the 

 peramelids while the others are common to the peramelids and certain 

 of the dasyurids. The total number of resemblances to the peramelids 

 therefore, is very large. Moreover, important distinctions between 

 C&nolestes and Perameles are comparatively few, being confined mainly 

 to the region between the sphenoidal fissures and to the proportions of 

 the processes of the mandible. 



In a number of respects the skull of Canolesles differs from all other 

 living marsupials. The most important of these are as follows: 



1. A preorbital vacuity between the nasals, maxillary, and frontal. 



2. A large mastoid foramen persisting in adults. 



3. A long narrow carotid canal between the petrous periotic and the 

 basioccipital. 



4. Floor of braincase very wide between sphenoidal fissures. 



5. Mastoid large and broadly exposed laterally (approached by 

 peramelids), 



6. Olfactory fossa relatively large and wide. 



DENTITION. 



Plate XVIII. 



The dentition and the cranium of Ccenolestes have been known since 

 the original discovery of the animal and have been variously described, 

 figured, and subjected to comment by different authors, notably 

 Thomas, Bensley, Sinclair, Dederer, and Gregory. The diprotodont 

 modification of its lower incisors combined with a polyprotodont upper 

 incisor formula and quadrate bunolophodont molars at once furnished 

 conditions not found elsewhere among living marsupials and not 

 typically representing either the diprotodont or the polyprotodont 

 group. The teeth have been well described in considerable detail by 

 Thomas (1895), but his specimen was somewhat affected by wear, 

 which obscured a few important points. For this reason and for the sake 

 of completeness and convenience of discussion full description of the 

 teeth is given in the following pages. Unfortunately it is still impossible 

 to give any information as to the succession of the teeth, since all the 

 specimens at hand are fully adult. 



