74 Psyche [June 
Since they were first made known to science in 1852 by Mulsant 
and Rey, through the description of Mesovelia furcata, there has 
been added one other species, described by F. B. White (9)! from 
the Hemiptera collected in the Amazons by Prof. J. W. Trail and 
named Mesovelia mulsanti. 
The information concerning the biology of these forms is meager 
and confined to a paper by Butler (2), 1893, on the “Habits of ~ 
Mesovelia furcata,”’ collecting notes on M. furcata by J. Scott (6) 
in England, and on M. mulsanti by Uhler (8) and by Bueno (1) 
in this country. It seems, therefore, worth while to present some 
notes concerning the biology of Mesovelia mulsanti whose habits 
and life-history are certainly among the most interesting of all the 
bugs that walk upon the surface of the inland waters. 
They may be separated from the other bugs of the surface film 
by the following synoptic table prepared by Mr. H. M. Parshley: 
A. Head as long as entire thorax; body and appendages extremely 
slender h:.2\. eis een EIR: Rotor cat Oma Hydrometride 
AA. Head shorter than thorax; form stout or moderately elongate. 
B. Claws inserted at apex of last tarsal segment. 
C. Antenne 5-segmented (except in Merragata); clavus 
membranous; membrane without veins..... Hebride 
CC. Antenne 4-segmented. 
D. Membrane without veins; hind cox rotatory; 
color greenish; wingless form common 
Mesoveliide 
DD. Membrane with distinct veins forming elon- 
gate cells; hind cox hinged; color not greenish; 
wings more or less developed........... Saldide 
BB. Claws inserted before apex of last tarsal segment. 
C. Hind femora not extending much beyond apex of 
abdomen; middle pair of legs about equidistant from 
front and hind pairs (except in Rhagovelia) size usually 
TATU GE so, VR ete Rene CY aE ee Veliide 
CC. Hind femora extending much beyond apex of ab- 
domen; middle.and hind pairs of legs approximated, 
very distant from front pair; size moderate, rarely 
TALLINE G oc a Ss tere cea Cre ada Aas ee Gerride 
1See Bibliography. 
