596 



SCIENCE 



[N. S. Vol. XXXII. No. 



SCIENTIFIC BOOKS 

 Medusce of the World. Volumes I. and II. 

 The Hydromedusse. By Alfred Golds- 

 borough Mayer. Published by the Car- 

 negie Institution of Washington. 1910. 

 No one could have approached this task 

 with a better equipment than has Dr. Mayer. 

 Serving for many years as the assistant and 

 companion of such a master as Alexander 

 Agassiz, naturally endowed with keen ob- 

 servational powers, possessed of very excep- 

 tional talent as an artist and enjoying the 

 familiarity with his subject which comes 

 from a careful study of a host of living forms 

 in many parts of the world, Dr. Mayer is as 

 well prepared as any man for a monographic 

 treatment of the Medusae of the world. 



The two quarto volumes under review con- 

 tain 498 pages of text, 30 pages of index, 55 

 colored plates and 327 text figures. One of 

 the most striking and satisfactory features of 

 the work is the very sensible plan adopted of 

 putting the plates where they logically be- 

 long — in the text with the descriptions and 

 discussions of the forms illustrated. This is 

 a concession to convenience and common sense 

 that is extremely refreshing; a practise ordi- 

 narily tabooed by publishers, but one that will 

 be welcomed by the actual users of books. The 

 plates themselves are just what was to be ex- 

 pected from Dr. Mayer's pencil and brush, 

 thoroughly satisfactory representations of these 

 exceedingly delicate and beautiful organisms. 

 The lines are in blue and the natural tints of 

 the colored parts are faithfully reproduced, 

 the author's exceptionally extensive acquain- 

 tance with the living medusse giving him a 

 rare power to express both their colors and 

 characteristic attitudes. 



The text figures are abundant and well 

 chosen. Many of them being tracings of the 

 drawings of other writers, they are necessarily 

 of less uniform excellence than the plates, al- 

 though they will prove exceedingly useful to 

 the practical worker in this group. 



The text gives a thoroughly monographic 

 treatment of the Hydromedusas, and the au- 

 thor is fully justified in his claim that " this 

 book aims to be something more than an old- 

 fashioned systematic treatise, for it attempts 



to record, if not to review, all works upon the 

 embryology, cytology, oecology, physiology, etc., 

 of all forms coming within the scope of the 

 text" (p. 3). 



In his systematic treatment the author has 

 found it necessary to frequently revise the 

 work of his predecessors, notably that of 

 Haeckel, the changes in the larger groups 

 being mainly in the combinations of the fam- 

 ilies of that writer. For example, Mayer's 

 Oeeanidffi =^ Margelidse + Tiaridae of Haeck- 

 el's classification, and Solmonidte of Mayer ^ 

 Solmonidffi + Peganthidse of Haeckel, thus 

 lowering several of the latter writer's families 

 to subfamily rank. The definitions are clear 

 cut and tersely put, being thus a distinct im- 

 provement on the verbose characterizations of 

 many monographic works. 



The numerous tables and keys to genera 

 and species will prove very helpful to workers 

 both in the Hydroida and Hydromedusse, in- 

 cluding the hydroid names of all of the 

 medusse so far as the former are known. Of 

 course it can not be expected that all of Dr. 

 Mayer's determinations will be acceded to by 

 other writers; but this matter can not be 

 properly discussed in the present review. In 

 general, however, it can be said that the au- 

 thor has shown a keen insight in his determi- 

 nation of the hydroid as well as the medusa 

 forms. There is something extremely canny, 

 moreover, in his treatment of the species of 

 particularly troublesome genera, e. g., Ohelia, 

 where he gives a tabular statement of the 

 characteristic of " the so-called species of 

 Ohelia," thus avoiding committing himself 

 unwisely on the one hand and drawing upon 

 his devoted head the thunderbolts of outraged 

 authors of species on the other. 



Something over 500 species are described, as 

 compared with 400 in Haeckel's great work. 

 This difference, however, does not properly 

 represent the number of new forms described 

 since the appearance of that monograph, as 

 Mayer's synonymy shows that he has often 

 combined several previously described species 

 in one, as in the case of Sarsie tuiulosa Les- 

 son, in which 8. mirabilis Agassiz is included 

 as a variety, besides five other species de- 

 scribed by various authors. 



