HYDROMETRIDAE 



553 



below the surface ; they can dive with facility, and are gregarious. 

 They are frequently found close to the shore, and Mr. Walker 

 has even met with them on land. The stink-glands of other 

 Hemiptera are said 

 by Nassonoff to be 

 replaced in Halobates 

 by peculiar ventral 

 glands. An allied 

 genus, Halobatodes, 

 was supposed to be 

 oceanic, but this is 

 not the case, some of 

 the species having 

 been found recently in 

 fresh water in India, 

 and others in estu- 

 aries at Port Darwin. 

 A remarkable allied 

 form, Jfermatobates 

 haddoni, was recently 

 discovered by Pro- 

 fessor Haddon in 

 Torres Straits. Apart 

 from the oceanic life, 

 Halolates is by no 

 means the most ex- 

 traordinary of the 

 Hydrometridae. The 

 Javanese Ptilomera 

 laticaudata repeats 

 some of its peculi- 

 arities, and is of larger size, with the sexes very different. The 

 most remarkable of the family is perhaps the fresh-water genus 

 Rheumatoljates (Fig. 266), in which the males have peculiar 

 prehensile antennae that look like legs. These curious Insects 

 inhabit North America and the West Indies. 



We may here notice an enigmatic Insect called Hemidiptera 

 haeckeli by Leon. From the single specimen known it is con- 

 cluded that the Insect has only one pair of wings, and that they 

 are attached to the metathorax. It is, however, possible, as 



FIG. 266. Rheumatobates bergrothi. x 10. 

 West Indies. (After Meinert.) 



