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. Ivirkaldy 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 allied 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 Kirkaldv 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 Metrobates 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 
exceedinglv short. 
The genus Halobatopsis was founded by Bianchi on the des¬ 
cription of the fresh water Gerrid Halobates 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 
difference, 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¬ 
what variable and on the w^hole they can be said to be of sub¬ 
equal length. The hemelytra of Halobates platensis are thus 
described bv 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 pictus. 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 
