22 THE VOYAGE OF H.M.S. CHALLENGER. 



creeping between rocks under water by the shore. A bug of the genus Halohates (fig. 

 35) is particularly common in these seas, besides the above-mentioned larvae of flies. 

 This genus was discovered by Eschscholtz, and now includes fourteen species living in seas 

 the most remote from each other. The species in question runs about like our Water- 

 Bug, Hydrometra, in great numbers and in every stage of development, on the high seas 

 hundreds of miles from land." 



And a note on p. 434 : " Eight species of the genus, as I am informed by my friend 

 Dr. Hagen, have been descril^ed ; that described in the text and discovered by me is a 

 new species and the largest of all. They are found in. the Atlantic, Indian, and Pacific 

 Oceans, as well as in the Chinese Sea, but only in tropical or sub-tropical regions." 



[Professor Semper tells me that the woodcut given in his work is a correct representa- 

 tion of the species referred to, and that the expression " now includes fourteen species " 

 was written by mistake. The species in question probably belongs to a new and unde- 

 scribed genus. — F. B. W.] 



In addition to the literature reproduced above, there are various other references to 

 the genus, but as they contain nothing of importance it is unnecessary to mention them 

 further. 



In addition to the specimens taken by the Challenger expedition, I have had the 

 advantage of having been able to study sjaecimens belonging to several museums and 

 private collections, both in Britain and on the continent of Europe ; and my best thanks 

 are due to all those who have in this and other ways assisted me. The museums to 

 which I am indebted for the loan of specimens are the following : — Berlin (through 

 Dr. Peters), Brussels (through M. A. de Borre), Liverpool (through Mr. T. J. Moore), 

 Oxford (through Professor Westwood), Stockholm (through M. C. Auri\dllius), Turin 

 (through M. L. Camerano), Vienna (through Dr. Eogenhofer). I have also to thank 

 Professor Westwood, of Oxford ; Dr. Signoret, of Paris ; Mr. J. W. Douglas, of London ; 

 and Dr. G. Hay, of Aden, for the loan or gift of specimens from their private collections ; 

 and for information and other assistance, Mr. John Murray of the Challenger ; 

 Mr. R. M'Lachlan, F.R.S. ; Dr. Murie, the Librarian of the Linnean Society ; Dr. 

 Dohrn, of Stettin ; M. L. Fau-maire, of Paris ; Dr. G. L. INIayr, of Vienna ; Mr. C. 

 Ritsema, of the Leydcn Museum ; Professor Semper, of Wiirzburg, Mr, J. T. Carrington, 

 F.L.S. ; the naturalists of the British Museum ; and lastly, Mr. Edwin Wilson, for the 

 painstaking skill with which he has drawn the illustrations. 



