June, 1908.] Guatemalan Hemiptera. 373 



however, in some Gerrid genera only of specific importance and 

 the posterior margin of the mesonotum is perfectly straight also 

 in Trepobates. Kirkaldy further adds: "The length of the 

 abdomen, moreover, will distinguish it from any of the smaller 

 Halobatitae." Unfortunately the author in his description gives 

 no statement whatever as to the length of the abdomen. But as 

 the genus Rheumatometra Kirk, (of which I have cotypes) differs 

 from the alhed genera by a multitude of characters not men- 

 tioned in the description, I think that this also may be the case 

 with Callistometra. In point of fact Kirkaldy states in the 

 specific description of C . Taylori that the last ventral segment 

 of the female is "roundly emarginate." This would indicate a 

 genus more nearly allied to Met rotates Uhl. and Telmatometra 

 Bergr. than to Trepobates in which the apex of the last female 

 ventral segment is truncate. The posterior femora of C. Taylori 

 are said to be "about seven and one-half times longer than the 

 tibiae." If this statement is correct the posterior tibiae are 

 exceedingly short. 



The genus Halobatopsis vv'as founded by Bianchi on the des- 

 cription of the fresh water Gerrid Haloba'tes platensis Berg and 

 is said to have the "first joint of the antennae about one-fourth 

 shorter than the second and third combined" whilst Trepobates 

 is stated to have the "first joint of the antennae not shorter than 

 the second and third combined." This would be a very slight 

 di Terence, unsupported as it is by other characters, and the an- 

 tennae of Trepobates are really variable to a certain extent, some 

 specimens agreeing with the diagnosis of Halobatopsis. Accord- 

 ing to Bianchi Trepobates has the "second joint of the antennae 

 about two-thirds of the third" and the "fourth joint of the an- 

 tennae distinctly longer than the third. "The mutual length of 

 the last three antennal joints of Trepobates is, however, also some- 

 Vvdiat variable and on the whole they can be said to be of sub- 

 equal length. The hemelytra of Halobates platensis are thus 

 described by Berg.: "Hemelytra basi biareolata, deinde venis 

 tribus longitudinalibus (vena media pliciformi) instructa." 

 This exactly fits Trepobates and there is nothing in Berg's des- 

 cription indicating that Halobates platensis is generically distinct 

 from Trepobates picttis. Ashmead has described a Canadian 

 species under the name Halobatopsis Begini. I am at a loss to 

 make out why he has placed it in the genus Halobatopsis Bianchi 

 as the first antennal joint, in direct opposition to the only generic 

 character given by Bianchi, is described as "distinctly longer 

 than joints 2 and 3 combined." The second joint, too, is said to 

 be "longer than the third, the latter being about three-fourths 

 the length of the second, " whereas platensis, the type of the pre- 

 tended genus, is described by Berg as having "articulo secundo 



