July 23, 1909] 



SCIENCE 



119 



governing the warping planes, and at the 

 other controlling the elevator. There is, 

 another controlling agent for the side rudders, 

 and yet another for the fuel supply to the 

 engine. The controlling mechanism is 

 grouped in such a manner as to afford easy 

 mastery over them, and Mr. Latham has 

 shown that he can travel in the air without 

 both hands being busily occupied. 



The eight cylinders of the engine are 

 grouped in two banks of four, arranged in V 

 fashion ; petrol is injected direct on to the in- 

 let valves, no carburetter being employed. 

 The fuel supply is governed by a pump of 

 variable throw, and the necessary air is sup- 

 plied through air pipes leading to the valves. 

 The water-cooling arrangement on the An- 

 toinette engine is also unique. Very little 

 water is employed, and it is quickly turned 

 into steam. This is carried away to an effec- 

 tive condenser, the tubes of which line the 

 side of the main body. The condensed water 

 is taken by a pump to the water tank, and 

 thence is pumped to the cylinder jackets. This 

 engine gives one horse power for about every 

 three pounds of weight. — The London Times. 



SCIENTIFIC BOOKS 



Revision of the Mice of the American Genus 

 Peromyscus. By Wilfred H. Osgood, 

 Assistant, Biological Survey. Prepared 

 under the direction of C. Hart Merriam, 

 Chief of Biological Survey, Department of 

 Agriculture. North American Fauna, No. 

 28. Washington, Government Printing 

 Office. April 17, 1909. Pp. 1-280, text- 

 figs. 1-12, pi. i.-vin. 



Mammalogists have awaited with eagerness 

 the long-delayed publication of Mr. Osgood's 

 monograph of the genus Peromyscus. The 

 work consists of a systematic study of all the 

 members of the genus, and includes keys for 

 the identification of the various forms, to- 

 gether with the necessary illustrations, and 

 maps showing the geographical distribution of 

 the species. 



Plate I. (colored) illustrates the distribution 

 of the species and subspecies of the Pero- 

 myscus mani<:ulatus group, plates II. to VIII. 



depicting the cranial and dental characters of 

 prominent species of the genus, and text-fig- 

 ures 1 to 12 portraying the geographical dis- 

 tribution of the various species and groups. 



As stated by the author: 



The American genus Peromi/scus, including the 

 so-called wood mice, deer mice, vesper mice or 

 white-footed mice, has needed revision for many 

 years. One or more of its numerous species and 

 subspecies inhabit almost every part of North 

 America; moreover, these mice, wherever found, 

 are among the most abundant of small mammals. 

 The group, therefore, is of such importance that 

 it must be dealt with in every work on North 

 American mammals, whether pertaining to classi- 

 fication, geographic distribution or economic rela- 

 tions. 



It is now about seven years since Mr. Os- 

 good undertook the revision of this great genus 

 of American murines, which has just been 

 brought to a most satisfactory conclusion. 

 During this time, in spite of many interrup- 

 tions, he has examined all of the specimens of 

 the genus Peromyscus in the great museums 

 of America and in numerous private collec- 

 tions, in the British Museum, and the mu- 

 seums of Europe, having unearthed Peromys- 

 cus types in the museums of Munich and 

 Zurich. 



In 1891, Dr. J. A. Allen, after discussing 

 certain species of Peromyscus, made the fol- 

 lowing statement: 



But the time has not yet come for a satisfac- 

 tory revision of the group, to attempt which at 

 least 20,000 specimens are requisite, collected so 

 as to fully represent the seasonal phases of pelage 

 obtaining at hundreds of more or less widely 

 separated localities. 



Mr. Osgood remarks : 



These conditions are now realized to the fullest 

 degree, for the number of specimens examined in 

 the present revision exceeds 27,000. The majority 

 of these are contained in the extensive collection 

 of the Biological Survey, which, under the direc- 

 tion of Dr. C. Hart Merriam, has been built up 

 with special reference to the various life areas of 

 North America, and without wliich no satisfactory 

 study of this group would now be possible. . . . 

 This material includes all the types, both of valid 

 forms and of synonyms, known to be in existence. 



