Reviews — Military Geology and Topography. 325 



species. These numbers, as well as those drawn from the British 

 Museum specimens, suggest that the position on post. Ad. II was 

 the more usual. Since either position is found in specimens 

 otherwise identical, the character cannot well be taken as diagnostic 

 of species. Neither does there seem any convincing reason for 

 regarding it as a secondary sexual character. 



When clearly seen, the gonopore has a pentagonal outline, 

 indicating that it was closed by five valves. In E 7632 it has 

 a slightly raised rim which appears toothed, perhaps owing to the 

 preservation of portions of the valves. In E 7636, the opening is 

 hexagonal. "When the pore pierces post. Ad. II, it is generally 

 flush or on a very slight eminence ; the latter feature is seen in 

 E 7631 (antea, fig. 24). When the pore is near the facet, it is 

 always on a rounded eminence, which in E 7630 and E 7634 is so 

 pronounced as to simulate the root of a young pelmatozoon. 



In two of the specimens the gonopore seems to be double. In 

 E 7630 (fig. 22), where it is on an eminence near the facet, there 

 is close beside it another smaller eminence with a pore. In E7635, 

 where it is on the left side of post. Ad. II, the appearance is rather 

 obscure, but there certainly seems to be a smaller opening to the 

 right of the main pore, and barely separated from it. 



As compared with Sinocystis, the position of the gonopore is here 

 slightly more definite, and in all cases is well above tbe periproct 

 (not on a level with it) and nearer to the subvective system. 



(To be continued.) 



REVIEWS. 



I. — Military Geology and Topography. Prepared and issued 

 under the auspices of the National Kesearch Council, Division 

 of Geology and Geography. Edited by Herbert E. Gregory, 

 Ph.D. pp. xv + 280. New York : Yale University Press. 

 London : Oxford University Press. Price 5s. 6d. net. 



THIS book was specially prepared in response to many requests 

 for guidance in the presentation of courses, required by the 

 Committee on Education and Special Training of the War Department, 

 for the training of officers for the new American Army. 



The list of collaborators in its preparation is a long and distinguished 

 one, including thirteen University professors and lecturers and several 

 well-known officers of the Geological Survey of the United States. 



A modest statement appears in the preface: "The book is the 

 result of a preliminary effort, and its authors hope that it will be 

 a nucleus about which will gather material for a more complete 

 volume." 



The fact that the American War Department recommended that 

 officers should be taught geology and geography is worthy of 

 attention. "When the entry of America into the War was decided 

 upon, American officers visited the Western Front to 6tudy conditions 

 and methods in order to profit by the knowledge gained for the 



