:i6 



SCIENTIFIC RESULTS FROM THE MAMMAL SURVEY. 



No. XVIII — {continued). 



Report on the House Rats of India, Surma, and Ceylon. 



BY 



Martin A. 0. Hinton. 



Part III. 



{Continued from page 416 of this Volume I) 

 Note on the Skull Measurements. 



In Table I are recorded the measurements of all the skulls 

 specially examined for the purposes of this paper. The worlv was 

 done by means of good sliding calipers, provided with a micrometer 

 screw fine adjustment, and a vernier reading 0.1 mm. accurately. 

 All measurements were made with the utmost care and the finer 

 ones under a w^atchmaker's glass ; many, at long distant dates, were 

 tested by repetition. With this and much other experience of 

 such work I believe that the margin of error is very seldom greater 

 than 0.05 mm. either way. 



The dimensions recorded are — 



1. Condylo-basal length. • 



2. Occipito-nasal length (from tip of nasal to most prominent 



point of occipital surface in mid-line). 



3. Greatest zygomatic breadth. 



4. Least interorbital breadth. 



5. Cranial width, taken just above squamosal roots of zygomata. 

 G. Greatest distance between temporal lines in fronto-parietal 



region. 



7. Least distance between temporal lines near interparietal. 



8. Occipital breadth. 



9. Median depth of occupit. 



10. Post-molar length ; condyle to m\ 



11. Auditory length ; condyle to front surface of bulla. 



12. Length of a nasal. 



13. Greatest combined breadth of nasals. 



14. Palatal length ; from most forward point of premaxilla to 



posterior edge of palate — NOT including median palatal 

 spine, when present. 



15. Length of diastema. 



16. Length of anterior palatal foramina. 



17. Greatest combined breadth of anterior palatal foramina. 



18. Breadth of rostrum in front of infraorbital canal. 



19. Least width of outer wall of infraorbital canal ( " masseteric 



plate" ). 



20. Length of molar series ; on crowns. 



