164 



name alone is a sufficient index of its value. The amount of 

 reifearch necessary to produce the work must have been enormous. 

 Every author who has written on this division of the Acarina for 

 the last hundred and fifty years is quoted and referred to. 

 According to Dr. Piersig, the family Hydrachnidae now reaches 

 fifty-eight genera, and upwards of six hundred species. In 

 addition to the detailed descriptions of these, keys are given for 

 the rapid identification of both genera and species, and any one 

 who has once tried to construct a key to a number of species will 

 realise the immense amount of work such an undertaking entails, 

 especially when it is stated that one genus alone, Arrhe7iurus, 

 contains seventy-nine species. 



Among the changes introduced by this work we notice that 

 there are three genera in which an alteration has been made in 

 the usually accepted spelling. Eylais is now Bulais, Krendowskia 

 is now Krenflowskija, and Arrenurus is now Arrhenurus. There 

 are also some very important alterations in the generic names : 

 Sperchonopsis is now Psendosp)erchon, and Fiona is now Lami7iipes. 

 We hope this latter name will be final, for this is the third 

 alteration since 1835. Coclileophorus^ a sub-genus of ^4^«x,Jias 

 been altered back to Neumayiia, the name given by Lebert in 1879. 

 Acercus has also been altered back to Tij^hys, Koch, 1835. But 

 perhaps the most important change is that the genus Curvipes 

 has been altered to Fiona. We may surely hope that this has now 

 found a resting-place. It is a genus containing a large number 

 of species which were at one time described under the name of 

 Nesaea, but Koenike in 1891 introduced the name Curvipes^ and 

 this was accepted by most writers. Now we are taken back to 

 Fiona, Koch's name for a portion of this genus. 



Such radical changes are very troublesome, but most of them 

 will in all probability be final. And as the work is a digest of 

 all the information, so far as species go, that exists in the 

 numerous scattered papers and books by writers of all nation- 

 alities, it is evidently one that no student of the Water-mites can 

 do without. CD. S. 



