84 ENTOMOLOGICAL NEWS. [Feb., '14 



group are usually stated. Thus the characters of the Submerged Vege- 

 tation Association are "in being distinctly aquatic and also essentially 

 independent of the bare bottom and of the surface," but "strictly de- 

 pendent upon the vegetation for nesting places, shelter, etc. The mud 

 minnow has been studied experimentally and shows avoidance of 

 light." The tendencies of this same association are toward change : 

 "This association, like all the others, is destined not to last ; changes 

 are taking place all the time. The chara is filling the pond at the rate 

 of one inch a year and is making a fine soil for roots of other plants. 

 As soon as the dense chara stage has existed for a time we find other 

 plants, such as Myriophyllum, Potamogeton, and water lilies. As soon 

 as these have become established we have the commencement of the 

 next association." Finally, the succession of animal life in the same 

 pond and the fate of the pond itself is considered and illustrated with 

 tables showing the occurrences of species in ponds of different ages. 



The terms "formation," "association" have here a technical ecologi- 

 cal significance and, just as there is a well-known series of taxonomic 

 groups of increasing magnitude (species, genus, family, order, class, 

 phylum), so there is employed in this book a series of ecological 

 groups, also of increasing magnitude (mos or mores, consocies, 

 stratum, association, formation, extensive formation) which, with the 

 exception of the first, bear not "the slightest relation" to the taxonomic 

 groups. They are defined on pages 37 and 38 but, we suspect, with no 

 greater exactness than has attended attempts at definition of the 

 taxonomic groups. 



As may be seen from the resume of the Pond chapter, change in 

 nature is emphasized throughout, the phenomena are dynamic, not 

 static. Ecological succession is often met in different parts of the book, 

 especially on pages 110-124. 



An interesting discussion is that of the efforts of ecologists, geog- 

 raphers and climatologists to find a method of measuring the environ- 

 ment of organisms which shall include a number of the most important 

 environmental factors. Dr. Shelford concludes that "the evaporating 

 power of the air is probably the best index of environmental condi- 

 tions of land animals" (p. 164). 



The author is best known to entomologists by his excellent work on 

 tiger beetles, but these are by no means the only insects employed in 

 characterizing ecological groups. The Index of Subjects is so ar- 

 ranged that one can quickly ascertain what members of a given group 

 are mentioned in the book. Thus under "Flies or diptera" are refer- 

 ences to fifty-one names of families and genera, alphabetically ar- 

 ranged. Almost all of the orders of insects, some of the Arachnids 

 and some Myriopods are represented, so that the book contains much 

 of interest to the entomologist. 



Owing to the numerous species cited and figured, the book is one 



