May 5, 1899.] 



SCIENCE. 



647 



•questions, however, can never be usefully- 

 determined until there exists on record a 

 basis on which to work, in the form of a 

 detailed description on each species accom- 

 panied, as far as practicable, by a figure. 

 The scheme, therefore, includes provision 

 for the publication of the scientific results 

 in a book uniform with the sumptuous vol- 

 ume which Dr. Anderson has recently issued 

 on the ' Eeptiles and Batrachians of Egypt.' 

 This work forms the first volume of the 

 ^ Zoology of Egypt.' He is at present en- 

 gaged in working out the collections of 

 mammals on which the second volume will 

 be based. The ' Fishes of the Nile ' will 

 form the third volume of this monumental 

 record of the fauna of the country. 



SCIENIIFIC BOOKS. 

 Birds. By A. H. Evans, M.A., Clare College, 

 Cambridge. London, Macmillan & Co., Lim- 

 ited; New York, The Macmillan Company. 

 1899. 8vo. 144 text cuts. Pp. xvi + 635. 

 Price, $3.50. 



Mr. Evans's ' Birds ' forms Vol. IX. of the 

 ^Cambridge Natural History,' and is intended 

 as a popular systematic review of the class 

 Aves. In a volume of 650 pages it is, of course, 

 impossible to treat in much detail any of the 

 one hundred and thirty odd families of birds, 

 or to particularize respecting many of the 12,- 

 000 to 13,000 or more species now recognized 

 by systematists. It would seem, however, that 

 a little more space might have been profitably 

 given to the generalities of the subject, as struc- 

 ture, classification, geographical distribution, 

 migration, etc., all of which is compressed into 

 the short space of twenty-two pages, of which 

 three are devoted to the terminology of the ex- 

 ternal parts of a bird. The remarks on classi- 

 fication and geographical distribution are mainly 

 historical. Mr. Evans adopts, with ' some 

 slight modifications,' Dr. Gadow's scheme of 

 classification and Sclater's scheme of geograph- 

 ical areas. In referring to the wide differences 

 of opinion among authorities on the subject of 

 genera and species he says: "It cannot be 

 denied that genera and species are merely 



'convenient bundles,' and that divisions of 

 either, if carried too far, defeat the object for 

 which classification is intended. Genera are 

 only more distinct from species, and species 

 from races, because the intervening links have 

 disappeared ; and if we could have before us 

 the complete series which, according to the 

 doctrine of evolution, has at some time existed 

 neither genus nor species would be capable of 

 definition any more than races in many cases ; 

 while the same remark will apply to the 

 larger groups. ' ' While such statements are not 

 new they have not been presented in popular 

 works, the lay reader being allowed to retain 

 the old idea of the tangible nature of generic 

 and specific groups. The tendency among 

 certain systematists to recognize subspecies on 

 the basis of the slightest recognizable differences 

 leads naturally to the multiplication of genera, 

 and the increase of subfamilies, etc., to con- 

 form, so to speak, to the new unit of measure- 

 ment consequentupon the recognition, in nomen- 

 clature, of the grade of differentiation that is 

 considered as a suflBcient basis for ' races ' or 

 subspecies. It is to this, doubtless, that Mr. 

 Evans alludes as being likely to ' defeat the 

 object for which classification was intended.' 



Beginning with Archxopteryx, and ending 

 with the Finches, the various groups of birds 

 are passed briefly in review. The characters 

 of the ordinal, subordinal and family groups are 

 succinctly stated, and some little account is 

 given of the number, distribution and habits of 

 the species, the latter usually in general terms. 

 Very little is said about any particular species, 

 though sometimes a characteristic member of a 

 group is taken as the subject of more definite 

 remark, or in cases where the number of species 

 is so few that something may be said of each. 

 The reader may be thus often disappointed, 

 in seeking information regarding particular 

 species, to find little, if any, reference to the ob- 

 ject of his search. In a work of the dimensions 

 of the present volume this must be inevitable, 

 yet it will prove a convenient source of 

 information on the general subject of bird life 

 throughout the world. References to more de- 

 tailed accounts of species or groups of particular 

 interest are, however, often supplied in foot 

 notes. Only about one-sixth of the work is de- 



