DISCUSSION" 



203 



TABLE 2— Continued 



OSTEOLOGICAIi DETAIL 



Lesser tuberosity. . 



Prox. medial ridge. 



Deltoid spine 



Deltoid ridge 



Epicondylar width , 

 Ulna 



Coronoid proc 



Tricipital proc 



Tricipital fossa — 



Brachial ridge 



Kadius 



Falciform 



Innominate 



Femur 



Lesser trochanter. 

 Tibia 



Semimembranous proc 



Popliteal fossa 



Lat. tibial fossa 



Groove, intern, malleol. 



Fibula (to notch) 



Head 



HOMODONTOMYS 



norm 

 norm 

 norm 

 norm 

 norm 

 norm 

 norm 

 norm 

 norm 

 norm 

 norm: norm 



present 

 norm 

 norm 

 norm 

 norm: norm 



norm 

 norm 

 .norm 

 norm 

 norm 

 norm 



NEOTO.MA 



lighter 



norm 



higher 



norm 



norm 



longer 



norm 



norm 



sharper 



norm 



shorter: 



lightest 

 present 

 shorter 

 norm 

 norm 

 shorter: 



lighter 

 norm 

 norm 

 shallower 

 shallower 

 longest 

 norm 



TEONOMA. 



norm 



sharper 



norm 



longer 



broader 



shorter 



sharper 



sharper 



sharper 



heavier 



shorter: 



heaviest 

 absent 

 shorter 

 longer 

 heavier 

 shortest: 



heavier 

 sharper 

 deeper 

 deeper 

 deeper 

 longer 

 larger 



Of the 62 osteological items tabled above, Neotoma, 

 considered on the whole as being the subgenus which 

 is the most intermediate in character, resembles Homo- 

 dontomys in 21 points, Teonoma in 12, and is inter- 

 mediate in 7. In 2 particulars does it differ from either, 

 while in 5 it shows the greatest development and in 15 the 

 least. These osteological variations are difficult of satis- 

 factory interpretation for the reason that there is variation 

 in the significance of almost every one of them. Thus a 

 dozen variations may be of far less importance phylogenet- 

 icaUy or adaptation ally than some single other, of equally 

 slight degree. After a careful consideration it seems 

 probable, however, that practically all of these 22 osteo- 



