J. R. DE LA TORRE BUENO. 243 



The GERRIOS of tlie Atlantic States (Subfamily 

 Gerriuic). 



BY J. R. DE LA TORRE BUENO. 



No entomologist, I suppose, who has collected in the free 

 open spaces and wandered afield in quest of his trophies, has 

 failed to see and notice, at one time or another, those strange 

 long-legged insects that walk the waters as though they 

 offered a solid surface to support them, and which we in this 

 country call," Water-striders." These insects, together with 

 other and smaller forms make up the family Gerridcs in the 

 great Heteropterous series, possibly one of the most remark- 

 able aggregations of species known to the entomologist. 

 Their haunts range from living springs, clear, secluded, 

 shady and cool, to the vast expanses of the tropic ocean 

 steaming under a torrid sun or lashed by wild storms into 

 mighty waves. These last Gerrids are members of a most 

 interesting tribe, the Halobatini, which occurs in all more or 

 less extensive bodies of water, but never, to my knowledge, 

 in currents of any kind. One of the oceanic forms visits our 

 own Southern coasts and certain lacustrine species are com- 

 mon inhabitants of our ponds and lakes. 



The family Gerridae differs from all the other Heteroptera 

 so far known from America, in having the claws sub-apical, 

 that is, inserted in more or less of a cleft at some distance 

 from the apex of the last tarsal segment. The heterogene- 

 ous assemblage of forms which ordinarily go under the name 

 of "water-striders," may be differentiated by the following 

 key, which presupposes some acquaintance in the field with 

 the various species and genera. 



KEY 

 to the families of the aquatic and semi-aquatic Trochalopoda 

 (Gymnocerata), or Littoralia of the old authors. 



1. (6.) Claws apical. 



2. (3.) Head much produced in front of eyes, slender delicate insects, 



winged or wingless Family HYDROMETRID^. 



TRANS. AM. ENT. SOC, XXXVII. 



