Febeuaey 14; 1902.] 



SCIENCE. 



267 



lum observations. Appendix No. 5 gives 

 the details of the resxilts secured. 



A special report on ' The Eastern Oblique 

 Arc of the United States was completed 

 and is being printed as a special publica- 

 tion. It is an important contribution to the 

 subject of geodesy. 



Satisfactory results have been obtained 

 at the astronomical observatories main- 

 tained under the direction of the Survey at 

 international expense, at Gaithersburg, 

 Md., and Ukiah, Cal., for the purpose of de- 

 termining the variation of latitude. 



The Survey has been represented by its 

 officers on commissions charged with the 

 marking of one international and two state 

 boundaries. 



The report refers to the reorganization 

 of the Office of Standard Weights and 

 Measures and its establishment as the Na- 

 tional Bureau of Standards by act of Con- 

 gress March 3, 1901. The principal reasons 

 for the change in order to meet the present 

 requirements of scientific and commercial 

 interests are summarized, and a description 

 of the functions of the new bureau and the 

 proposed buildings and accessories is given 

 in detail. 



SCIENTIFIC BOOKS. 

 A Treatise on Zoology. Edited by E. Eay 

 Lankestee. Part IV. The Platyhelmia, 

 Mesozoa, and Nemertini. By W. Blaxland 

 Bekham^ D.Sc, M.A. London, Adam and 

 Charles Black, Publishers ; New Tork, Mac- 

 millan & Company. Pp. 204. 114 figs, in 

 text. Price $5.25. 



Volume IV. of Lankester's valuable series 

 well maintains the standard set by the parts 

 previously issued, and the lower divisions of 

 the old group 'Vermes' are here treated in a 

 broad and suggestive manner by a well-known 

 helminthologist. The author deserves the 

 gratitude of all zoologists for bringing to- 

 gether in a concise but comprehensive form 

 the many facts that have been accumulated 

 in connection with these lower forms of In- 

 vertebrata. 



From the nature of the subjects treated the 

 text is necessarily disconnected, but each divi- 

 sion is accurately set forth in respect of the 

 structural modifications and types, and each 

 is complete in itself. The divisions which are 

 thus separately treated are : Turbellaria, Tem- 

 nocephaloidea, Trematoda, Cestoidea, Nemer- 

 tini, and appendices to the Platyhehnia, includ- 

 ing Rhombozoa (Dicyema, etc.), Orthonectida, 

 Trichoplax, Salinella, etc. The author adopts 

 Lang's classification of the Turbellaria into 

 Ehabdocoelida, Tricladida and Polycladida; 

 Monticelli's orders of the Trematoda, and Biir- 

 ger's divisions of the Nemertini. The greatest 

 changes are to be found in the Cestoidea. 

 Here Lang's 'orders' Cestoda monozoa and 

 Cestoda polyzoa are changed to the 'grades' 

 Cestoda monozoa and Cestoda merozoa, while 

 each is further divided into sections and or- 

 ders. Among the monozoa we find the orders 

 Ampliilinacea, Gyrodactylacea and Caryo- 

 phyllacea based upon the characters of the 

 genera similarly named. The merozoa are fur- 

 ther subdivided into sections Dibothridiata 

 and T etrdbothridiata according to the number 

 of sucking cups or 'bothria.' In the former 

 there is one order, Pseudophyllidia of van Bene- 

 den, while in the latter the number of orders 

 is raised to four: Tetraphyllidia, Diphyllidia, 

 Tetrarhyncha of van Beneden and Tetracotylea 

 of Diesing. (Tseniidae auct.) 



We are particularly pleased with the substi- 

 tution of the term 'merozoa' for Polyzoa in 

 the classification of Cestoidea and it should do 

 away with the confusion of terms among 

 English-speaking zoologists who adhere to 

 Thompson's term Polyzoa for an order of the 

 MoUuscoida. The use of the term 'Mesozoa' 

 in the title of the book is less satisfactory for 

 it perpetuates the probable error of regarding 

 a small group of parasitic and degenerate 

 forms of Platyhehnia (?) as 'intermediate' 

 or primitive types, notwithstanding that this 

 view is strongly attacked in the text, where the 

 word appears only in an historical sense. 



An innovation of great value is the intro- 

 duction of a concise historical statement, in 

 which are given the names and dates of the 

 men who have added to our knowledge of each 

 of the classes considered; and still another 



