June, 1908.] Guatemalan Hemiptera. 371 



To make any comment on Dr. Bergroth's finished work "were 

 to paint the hly," nevertheless a few remarks for greater clear- 

 ness may not be out of place. The paper in question, while based 

 on some of the Guatemalan material does not cover all the speci- 

 mens, nor give all the records, since only a few of the Trepobates 

 were sent, with others from Arizona. The other localities will 

 appear in the systematic part of the list. 



In reference to Rheumatobates , the brush at the inner end of 

 the fore tibia is also to be found in other Gerridae and its use 

 appears to be for cleaning the antennae at least, an operation 

 repeatedly observed by me in Microvelia americana Uhler. 

 While their apparently preferred habitat is in running waters, 

 in my experience Rh. rileyi appears to prefer coves and slack 

 waters along the banks of the streams it frequents. Neverthe- 

 less, I have found it abundant in a lake in New Jersey, in places 

 where there was no current, so it would appear to me that it is 

 not altogether impossible to breed them. Dr. Bergroth also 

 very fullv described the winged form of Rh. tenuipes Meinert, of 

 which and also of rileyi, I possess specimens. But I have 

 also taken a brachypterous form in this latitude, in which the 

 hemelytra do not reach the end of the abdomen, being appar- 

 ently truncate. In some subsequent paper, -I hope to be able 

 to more fully elucidate these points. 



FAMILY GERRIDAE. SUBFAMILY HALOBATINAE. 



E. Bergroth. 



To this subfamily I refer only the genera having the inner 

 margin of the eves convexly rounded. In the subfamily Gerrinae 

 the ocular orbita is arcuately sinuate behind the middle. Mayr 

 (Reise d. Novara, Hem., p. 169) was the first who based the 

 primarv subdivision of the Gerridae on this character. But 

 little attention has been paid to it by Bianchi and Champion, and 

 none at all bv Distant in his Fauna of British India, but it is 

 carefully indicated in Kirkaldy's generic descriptions. As char- 

 acter for the two subfamilies Bianchi solely gave (in which he was 

 followed bv Distant) the breadth of the body compared to its 

 length, a feature entirely unsatisfactory as justly observed by 

 Champion who does not accept the subfamilies. Of the genera 

 included in the Halobatinae by Bianchi at least one — Pota- 

 mometra Bianchi — really belongs to the Gerrinae. I may be mis- 

 taken, but I believe that the character derived from the form of 

 the eves, slight as it may seem, is indicative of a real affinity 

 between the genera having these organs similarly built and I 

 also believe that this rather trivial character could be supported 

 by others when these polymorphous, as yet little known and little 

 understood insects have undergone a thorough and much needed 



