772 



SCIENCE. 



[N. S. Vol. V. No. 124. 



means claim, on the strength of such evidence, 

 a common origin for them, but merely present 

 the facts as 'food for reflection.' " 



In discussing the extraordinary conditions 

 presented in the genus Geospiza, Mr. Ridgway 

 states: " When it is remembered that the col- 

 oration is practically, if not absolutely, the 

 same in all of the twenty-odd forms of the 

 genus Geospiza, it will be seen that if any segre- 

 gation of species is made at all it must be based 

 upon measurements ; and when it is further 

 seen that there is a gradual transition from the 

 enormous beak of G. magnirostris to the com- 

 paratively minute one of G. parvula and from 

 the excessively thick one of G. pachyrhyncha 

 (whose lateral outlines approximate an equi- 

 lateral triangle) to the slender and curved one 

 of G. scandens or the acuminate one of G. 

 acutirostris ; and that size of beak is not neces- 

 sarily correlated with length of wing, tarsus, 

 etc., the difficulty of defining species becomes 

 obvious. * * * Having been perplexed by 

 these difliculties I have carefully weighed all 

 doubtful cases, and whenever there seemed to 

 be a well defined average difference between 

 specimens from different islands I have not 

 hesitated to separate them as local forms. No 

 other course, indeed, is practicable ; for were 

 ' lumping ' once begun there could be no end to 

 it, unless purely arbitrary limits were given to 

 the species recognized, and if followed to a 

 logical conclusion might easily end in the recog- 

 nition of a single variable species, equivalent 

 in its limits to the genus. ' ' 



In an earlier paper Mr. Ridgway united the 

 genera Cactornis and Geospiza because of inter- 

 gradation ; in the present paper Cactornis is re- 

 tained in a subgeneric sense. Mr. Ridgway 

 quotes a letter from Dr. Baur as follows : 

 "You place the species of these two genera in 

 one genus, Geospiza. I do not think that this 

 is natural. Both have their peculiar represent- 

 atives on the different islands, and if you 

 place them together this peculiar differentiation 

 of each is lost sight of. Cactornis is more 

 slender than Geospiza and has many more 

 black individuals. I would keep the two 

 genera apart." Dr. Baur might have strength- 

 ened his position by adding that genera should 

 be based on degree of differentiation rather 



than on the survival or non-survival of inter- 

 grades. The present case is unusually ex- 

 treme, because a complete chain of intermedi- 

 ate ' species ' is known to exist, connecting the 

 slender-billed Cactornis type with the thick- 

 billed Geospiza type. But in all cases of de- 

 rivative genera the theory of evolution, con- 

 ceived on these very islands, calls for the 

 existence at one time or another of similar 

 chains of intergrades. Whether such inter- 

 grades survive, bridging the extremes with 

 living forms, or die off, leaving the extremes 

 trenchantly defined, is a matter of zoological 

 interest, but one in no way affecting the degree 

 of differentiation of the extremes, on which 

 alone, in my judgment, the question of generic 

 distinctness should rest. 



Chronologic lists of the species found on each 

 island by the various explorers, from Darwin 

 in 1835 to Townsend, Baur and Adams in 1891, 

 are given, and also an exceedingly convenient 

 tabular statement showing in 16 columns the 

 various islands on which each of the 105 

 species is known to occur. This is followed by 

 the systematic part of the paper, comprising 

 keys, maps and careful descriptions of the 

 various genera and species. The map used is 

 a skeleton, covering considerably more than a 

 half page, on which range is indicated by 

 heavy-face numerals. Since this map is intro- 

 duced about 50 times the waste space at the 

 top and bottom adds materially to the size of 

 the paper. Two plates are given showing the 

 astonishing variations in the size and form of 

 the bill in the genera Nesomimus, Camarhynchus 

 and Geospiza. The paper closes with a bibli- 

 ography of 23 titles. The technical descriptions 

 are models of thorough painstaking work, and 

 the memoir as a whole easily takes a place 

 among the classics of ornithology. 



By an utterly unpardonable blunder, for 

 which the author is in no way responsible, the 

 cover-title-page is dated 1896, although not 

 published until March, 1897. Accidents are 

 liable to occur anywhere, but the number of 

 papers bearing the cherished imprint of the 

 Smithsonian Institution which are permitted to 

 appear under ostensible dates that materially 

 antedate the actual date of publication is not 

 only an injustice to the author and an annoy- 



