4 Bulletin American Museum of Natural History [Vol. XLII 



tributed by Garman, Riley, and Matheson on Hydrous triangularis: 

 by Wickham on Tropisternus glaber; by Wickham and Bowditch on 

 Hydrocharis obtusatus; and by Boving on Hydroscapha natans. 



In Europe there has been more activity.. The work of Schiodte, 

 1861-1872, stands foremost and his results have been well supplemented 

 by that of Balfour-Browne, Megusar, Miall, Planet, Duges, Reitter, 

 Ganglbauer, and d'Orchymont. Schlick, Wesenberg-Lund, and Boving 

 in Denmark have reared much important material, most of which has, 

 through the efforts of Dr. Boving, been deposited in the National 

 Museum at Washington. They have, however, published very little of 

 their results. 



The most valuable papers of today are those of Ganglbauer and 

 d'Orchymont. The former's paper gives a lengthy survey of the family, 

 based on the life histories as well as on adult structures. The latter's 

 work presents new life histories in a number of genera, careful descrip- 

 tions and figures, a discussion of the larval breathing apparatus, and a 

 generic key to the known larvae. Balfour-Browne has given the most 

 complete treatise on any one species. He treats the entire life history of 

 Hydrobius fuscipes from egg to adult, describing each stage and its 

 biology in full and accompanies the whole with excellent figures. 



It seems advisable to mention only the most important authors at 

 this point. The others will be considered under the biology of the 

 separate genera. 



