120 



SCIENCE 



[N. S. Vol. XXX. No. 760 



In almost all cases in which no types exist, good 

 series of topotypes, or specimens from near the 

 type localities, have been available. 



Mr. Osgood's study of this wealth of ma- 

 terial has resulted in a definite expression of 

 the characters of the species and geographic 

 forms of Peromyscus, almost the last impor- 

 tant genus of North American mammals 

 which has remained to be systematized by a 

 trained mammalogist in possession of an 

 abundance of well-prepared and carefully- 

 selected specimens. 



The chaotic condition of Peromyscus can 

 best be illustrated by a quotation from the 

 author's introduction, under the caption of 

 ■" History and Nomenclature " : 



In fact, no fewer than 167 names for new or 

 supposed new forms of Peromyscus have been pro- 

 posed since 1885. Add to this the 14 contained 

 in the present paper, and the total of 181 is 

 reached. ... Of the 167 names [excluding those 

 proposed by the author in the present monograph] 

 for supposed new forms of Peromyscus proposed 

 since 1885, 58, practically one third, are of more 

 than doubtful status and are here treated as 

 synonyms. 



The subject matter is presented under the 

 following headings: Introduction, Material, 

 History and Nomenclature, Variation, Inter- 

 gradation, Pelages, Color Descriptions, Meas- 

 urements, Keys, Eecords of Specimens, Sub- 

 genera, Habits and Economic Status, List of 

 Species and Subspecies with Type Localities, 

 New Subspecies, Genus Peromj/«c us. Subgenus 

 Peromyscus, Subgenus Megadontomys, Sub- 

 genus Ochrotomys, Subgenus Podomys, Sub- 

 genus Haplomylomys, Subgenus Baiomys and 

 Table of Measurements. 



The paper, throughout, has the advantage 

 of being written in simple language adapted 

 to the use of ordinary workers, to whom hints 

 of practical value are being continually thrown 

 out, the author happily having adopted the 

 principle of helping rather than impressing 

 his readers. There is also a pleasing element 

 of fairness, and impartial weighing of evi- 

 dence, when dealing with the writings of pre- 

 vious authors, which reflects the personality 

 of the author. 



The folded map (Plate I.) showing, in 

 colors, the distribution and intergradation of 

 the 39 subspecies of Peromyscus maniculatus 

 must excite the astonishment and delight of 

 mammalogists, inasmuch as showing that, at 

 last, we have acquired enough specimens of 

 one large and complex group to illustrate its 

 interrelations. Many of the named forms 

 which Mr. Osgood has placed in synonymy 

 represent the wavy lines, which, in his col- 

 ored diagram, show " areas of intergradation." 

 Who, years ago, could have imagined that 

 Peromyscus canadensis Miller {^Peromyscus 

 maniculatus gracilis) and Peromyscus palli- 

 dus Allen could possibly be proved to be con- 

 specific forms, actually intergrading through 

 the subspecies maniculatus, arcticus, nehras- 

 censis, luteus and hairdi? Again, in 1890, the 

 reviewer described arcticus as a subspecies of 

 leucopus, and, the same year, Merriam ven- 

 tured to separate rufinus from leucopus as a 

 subspecies. Now we know that these forms 

 are distinct from the species leucopus and 

 belong to the then unrecognized species man- 

 iculatus. This knowledge is due to the pos- 

 session of adequate and carefully-studied ma- 

 terial. 



An important feature of Mr. Osgood's mono- 

 graph is the wonderful key to Peromyscus, 

 which is one of the best of its kind. With it, 

 one can open the Peromyscus cage with the 

 certainty that the particular white-stockinged 

 little mouse wanted will prance out at the 

 simple turn of the wrist. One can not fail to 

 admire the ingenious construction of this key 

 that actually works the combination. 



As a reviewer, I suppose I ought, in self- 

 defense, to find some fault with a monographer 

 who has had the temerity to relegate several 

 forms described by myself to the category of 

 synonyms; but I have not the disposition to 

 find fault with a work of such practical utility 

 and completeness, planned on uniform lines, 

 and carried out to such a satisfactory conclu- 

 sion. It is really straining a point when, for 

 instance, I assert that, in my opinion, Pero- 

 myscus eremicus arenicola should have been 

 recognized as a valid subspecies of the Eastern 



