106 GIDLEY 



agree with the general sentiment expressed {of. ctt., p. 366) 

 that, owing to the adoption of different plans in different groups 

 of mammals for increasing the complexity of their molars, no 

 terminology founded on the basis of cusp homologies can be 

 made strictly applicable to all the mammalia. I do not, how- 

 ever, consider this sufficient ground for abandoning absolutely 

 so convenient a system of nomenclature as that proposed by 

 Osborn. Granting that many of the terms proposed are founded 

 on mistaken homologies, it does not necessarily follow that they 

 need be in the least confusing, as suggested by Wortman. For 

 in any system used, in order to make that system of greatest 

 convenience and highest utility, the names once adopted should 

 be permanent and not subject to transfer or substitution on any 

 ground of changed conceptions of homologies or history, for 

 the same reason that generic and specific names are retained 

 regardless of the fact that they may have been given to denote 

 some supposed affinity or characteristic which may later have 

 proved entirely erroneous. 



Viewed from the nomenclature standpoint, therefore, the 

 convenient names proposed by Osborn have come to assume an 

 individuality which conveys a far more definite meaning than 

 any purely descriptive terms, be they of relative position or 

 supposed homologies. Moreover, they have the valuable ad- 

 vantages of clearness and brevity in description. On these 

 grounds, in the opinion of the present writer, and for the added 

 reason that great confusion would inevitably result from any 

 change in a terminology that has found its way into so many 

 publications, Osborn's nomenclature should be retained as orig- 

 inally proposed. Thus the term "protocone" always means 

 the main antero-internal cusp of a normal upper molariform 

 tooth, whether that element is regarded as the original primary 

 cusp or otherwise. 



The objection that the terms are not universally applicable is 

 scarcely worthy of consideration since they are widely appli- 

 cable to the great majority of mammalian molar types, without 

 in the least interfering with the use of terms descriptive of " rel- 

 ative position only," which may be used in any cases where Os- 

 born's terms do not apply. 



