May 14, 1897.] 



SCIENCE. 



753 



valleys by the measure of some multiplier 

 much greater than unity. When valleys 

 are irregular the basal retardation is still 

 further increased and the movement of the 

 ice is correspondingly transferred to the 

 upper horizons. The irregularities of the 

 coast of the region in question give this 

 fact special application. The interpretation 

 of the author is, therefore, quite consistent 

 with a limited extension of the ice border, 

 but quite inconsistent with profound exten- 

 sion. The whole of the phenomena de- 

 scribed in the paper are precisely concord- 

 ant with moderate extension. They are as 

 precisely discordant with great extension. 



The remainder of the paper consists of a 

 description of the Cornell glacier, of the 

 evidences and amount of former invasion, 

 of the recent advance and retreat of the ice, 

 and of the evidences of present retreat of 

 the Cornell glacier. This portion embraces 

 much valuable data, unless it is vitiated, as 

 it probably is not, by the lack of care which 

 marks the controversial part. It is ac- 

 companied by excellent photographs, all of 

 which, as the writer would interpret them, 

 show evidences of greater or less glacial 

 modification of contour. 



T. C. Chambeelin. 

 Univeesity of Chicago. 



SUGGESTIONS FOB A NEW METHOD OF DIS- 

 CRIMINATING BETWEEN SPECIES AND 



SUBSPECIES. 

 According to present usage the rule 

 which determines whether a particular 

 animal or plant shall stand in our books as 

 a species or subspecies may be stated as 

 follows : Forms knoivn to iniergrade, no matter 

 how different, must be treated as subspecies and 

 bear trinomial names ; forms not knoivn to inter- 

 grade, no matter how closely related, must be 

 treated as full species and bear binomial names. 

 This principle was first distinctly formu- 

 lated in the Code of Nomenclature of the 

 American Ornithologists' Union, published 



in 1886. In the remarks that follow, the 

 authors of the Code state : " The kind or 

 quality, not the degree or quantity, of differ- 

 ence of one organism from another de- 

 termines its fitness to be named trinomially 

 rather than binomially. A difierence, how- 

 ever little, that is reasonably constant, and 

 therefore ' specific ' in a proper sense, may 

 be fully signalized by the binomial method. 

 Another difference, however great in its 

 extreme manifestation, that is found to 

 lessen and disappear when speciniens from 

 large geographical areas or from contiguous 

 faunal regions are compared is, therefore, 

 not 'specific,' and, therefore, is to be provided 

 for by some other method than that which 

 formally recognizes ' species ' as the ulti- 

 mate factors in zoological classification. In 

 a word, intergradation is the touchstone of 

 trinomialism." 



Eleven years have now elapsed since the 

 publication af the A. O. TJ. Code of Nomen- 

 clature, in which the above canon and 

 statement were first published. During 

 this period the plan advocated has been very 

 thoroughly tested, not only by ornitholo- 

 gists, but by systematists in many other 

 departments of zoology, and also in botany. 

 The time has come, therefore, when it should 

 be possible to examine its practical work- 

 ings, with a view to ascertaining whether 

 or not the system is satisfactory. 



In practice it has been found that only in 

 a small percentage of cases does an author 

 have at his command a sufficiently large 

 series of specimens, from a sufficient num- 

 ber of well-selected localities, to enable him 

 to say positively that related forms do or 

 do not intergrade. The result of this ob- 

 vious embarrassment is that authors usually 

 exercise their individual judgment as to the 

 probable existence or non-existence of in- 

 tergradation, thus introducing the personal 

 equation it was hoped to avoid. The natural 

 result is a degree of inconsistency in the use 

 of trinomials which has formed the subject 



