Measurement of ribs. 



61 



und 9 mill, are tlie greatest breadths lur the 2""*, H"' and 4'*' ribs. 

 7 mm., 7 nini, and 4 mm. tor tlu* r>"*, 6"' and 7"^. These breadths 

 are al)oiit 15 mm. above the margins. 



The breadths fall otl' quickly below this. 



Behind the seventh the ribs are much narrower tangentially. 



Where the ribs are very broad they are also very thin and the 

 intercostal spaces are narrower ; of course all these notes are taken in 

 the dry skeleton. 



The 2"*^ rib is thinned below at the expense of the anterior 

 surface. In the rabbit the breadths of the ribs do not vary much as 

 far as the ninth. The lower three are smaller. (Krause ^). 



Arctomys Mai-mota. The radial breadths are the most considerable. 

 In the lower thirds the posterior surfaces turn outwards. The greatest 

 diameters are near the angles and the lower ends. In the middle of 

 their lengths the ribs are narrow. 



The Flying Squirrell (Pteromys). 



The posterior four have a uniform breadths from the tubercles to 

 the angles (PI. U. fig. 5). 





1 



2 



3 



4 



5 



6 



7 



8 





Â 



10 



20 



30 



40 



50 



55 



60 



55 





B 



10 



17 



17 



23 



25 



34 



47 



55 



The ninth rib shows a slight 

 increase in the breadth a little below 



c; 



3 



2 



2 



2^ 



2,5 



2,6 



2,5 



2,b 



the tubercle, where it measures 3 mm. 



1) 



3 



3 



4 



6 



5 



4 



3,5 



3,3 



The others are about 2 mm. each. 



£ 



— 



15 



25 



32 



45 



45 



45 



45 





Centetes Ecaudatus. Tanree. 



10 



.A ;! 15 , :i.) L'y , 4(J 45 50 50 ! .52 : 50 48 



n " 8 9 12 1 17 I 25 .27 I 30 



30 i 35 



8,5 



3 3 12,5 2,5 2 2 2 2 



11 



12 



lii. 



42 

 2,5 



14 15 16 



38! 35 



- ! _ 



2,5 1 2,5 



30 

 2,5 



2 ' 2 1,5 1,5 1 



17 



18 

 22 



*) Anatomie des Kaninchens. 



