OCTOBEK 3, 1913] 



SCIENCE 



463 



dilemma the morphologist has, of course, 

 introduced the differential of descent, 

 whether homologous or analogous, into his 

 diagnoses of organs. 



The same principles must apply to the 

 classification of the animals. To group the 

 various representative owners of cases of 

 isotely together under one name, simply 

 because they have lost those characters 

 which distinguished their ancestors, would 

 be subversive of phyletic research. It is of 

 the utmost significance that such "con- 

 vergences" (rather "mergers," to use an 

 administrative term) do take place, but 

 that is another question. If it could be 

 shown that elephants in a restricted sense 

 have been evolved independently from two 

 stems of family rant, the convergent ter- 

 minals must not be named Elephantinw, 

 nor can the representatives of successive 

 stages or horizons of a monophyletic family 

 be designated and lumped together as sub- 

 families. And yet something like this 

 practise has been adopted from Cope by 

 experienced zoologists with a complete dis- 

 regard of history, which is an inalienable 

 and important element in our science. 



This procedure is no sounder than would 

 be the sorting of our Cartwrights, Smiths 

 and Bakers of sorts into as many natural 

 families. It would be subversive of classi- 

 fication, the aim of which is the sorting of 

 a chaos into order. We must not upset the 

 well-defined relative meaning of the classifi- 

 eatory terms which have become well-estab- 

 lished conceptions; but what such an as- 

 sembly as the terminal elephants should be 

 called is a new question, the urgency of 

 which will soon become acute. It applies 

 at least to assemblies of specific, generic 

 and family rank, for each of which grades 

 a new term, implying the principle of con- 

 vergence, will have to be invented. In 

 some eases geographical terms may be an 

 additional criterion. Such terms will be 



not only most convenient, but they will at 

 once act as a warning not to use the com- 

 ponent species for certain purposes. There 

 is, for instance, the case of Typhlops 

 hraminus, mentioned at the beginning of 

 this address. Another case is the dog spe- 

 cies, called Canis faniiliaris, about which 

 it is now the opinion of the best authori- 

 ties that the American dogs of sorts are the 

 descendants of the coyote, while some In- 

 dian dogs are descendants of a jackal, and 

 others again are traceable to some wolf. 

 The "dog," a definable conception, has 

 been invented many times, and in differ- 

 ent countries and out of different material. 

 It is an association of converged hetergene- 

 ous units. We have but a smile for those 

 who class whales with fishes, or the blind- 

 worm with the snakes ; not to confound the 

 amphibian CcBcilians with reptilian Am- 

 phisbcenas requires some training; but 

 what are we to do with creatures who have 

 lost or assimilated all those differential char- 

 acters which we have got used to rely upon 1 



In a homogeneous crowd of people we 

 are attracted by their little differences, 

 taking their really important agreements 

 for granted; in a compound crowd we at 

 once sort the people according to their 

 really unimportant resemblances. That is 

 human nature. 



The terms "convergence" and "paral- 

 lelism" are convenient if taken with a 

 generous pinch of salt. Some authors hold 

 that these terms are but imperfect similes, 

 because two originally different organs can 

 never converge into one identical point, 

 still less can their owners whose acquired 

 resemblance depresses the balance of all 

 their other characters. For instance, no 

 lizard can become a snake, in spite of ever 

 so many additional snake-like acquisitions, 

 each of which finds a parallel, an analogy 

 in the snakes. Some zoologists therefore 

 prefer contrasting only parallelism and 



