34 Bulletin American Museum of Natural History. [Yo\. XX^'II, 



loco pinnce pectoralis" is the first character listed, and the nature of the 

 extremities is thus taken as a prime criterion. This ilhistrates Linnseus's 

 dictum that a character of sUght importance in one order may become 

 fundamental in another. 



Summary ofLimie's contributions to the ordinal classification of the mammalia. 



Linne's debt to Ray is clearly shown in his use of the number of front 

 teeth as an important criterion, but he progressed much beyond Ray, Klein 

 and Brisson in the variety of characters chosen to define his orders. As we 

 have seen, the ordinal characters include: (1) nature of the food and mode 

 of obtaining it, generally as the dominating character; (2) the number of 

 front teeth and of laniary teeth; (3) the nature of the extremities, whether 

 hands (Primates), clawed feet (Ferte), hoofs (Pecora) fins (Cete); (4) the 

 manner of progression e. g., climbing trees (Primates), "more or less awk- 

 ward" (Bruta), "ravenously snatching the prey" (Ferse), "hopping" (Glires), 

 "heavy" (Bellute); (5) the number and position of the mammae (Primates); 

 (6) the presence of clavicles (Primates); (7) the nature of the stomach 

 (Pecora); (8) the nature of the teeth ("gristly" in Cete); (9) the nature of 

 the nostril (Cete). 



Linnseus must have recognized that the ordinal classification of the 

 mammals was a difficult problem. This is shown by the conspicuous changes 

 and redistributions which he made betw^een the first and tenth editions of the 

 'Systema,' and further by the fact that his pupil Erxleben abandoned the 

 ordinal divisions entirely and merely listed the genera seriatim. The diffi- 

 culty of the problem is in fact indicated by the circumstance that Cuvier, 

 with far better material and more extensive knowledge, was constantly 

 deceived by "adaptive" (or homoplastic) resemblances, while even the late 

 Professor Cope, who wrote much on homoplastic and convergent evolution 

 was himself often so deceived. 



Accordingly many of the characters selected for ordinal diagnoses by 

 Linnaeus and all other early winters were of the adaptive or "csenotelic" 

 kind (p. Ill) which are now known to have been most easily modifiable by 

 changes in the environment or in internal conditions. The reason for this 

 mistake (from which few naturalists were free even down to our ow^n genera- 

 tion) was that Linnaeus regarded the mode of sustenance of a group as one of 

 its most deep-seated attributes, most surely indicative of more or less hidden 

 affinities with other groups. Like Storr, he proceeded from the basis that 

 "because modifications had certain evident relations to the economy of the 

 animal, they were, therefore, and to the degree of their physiological influ- 

 ence, of importance in determining the affinities of those animals." (Gill, 



