106 THE UNIVERSITY SCIENCE BULLETIN. 
Following is given a table of measurements of the various instars and 
of the adults: 
TABLE OF MEASUREMENTS IN MILLIMETERS OF INSTARS OF MESOVELIA MULSANTI. 
see Antenne. Hind leg. Middle leg. Fore leg. 
=o = 1 Tr Gay 
Stage. BB 2 = = = g es = g = S g = = 
z B eI Fs a 2 2 : E Fo 2 E Fo 2 Eee E 
ae 
S5 : 
1st instar....! 1 149 099 11 416 416 Dl v2 336 306 166}.25 |.213}.129 
2d instar..... 1°25 20 125 20 54 625) .225 35 343 188! 312} .2 135 
odknstars- 2 )|) ls 25 166 207 54 625 85 210 437 44 225] .375!.33 |.167 
4th instar....| 2.125 29 21 32 75 81 | 1 375 625 625 29 |.5 38 |.25 
Dihanstareey | eee solo 29 SOx) Mest lB! BPR i/ PAST alo m3) .375| .625].50 |.26 
Gthi(male) ey. sige 65 S16 Lb) 9 296n tesa)! 156 45) 1.09 | 1.09 .416] .858].75 |.26 
6th (female). }...... 59 39 65 Oe le S695 LOD wl a lide idee Lees -52 1.91 1.78 |.312 
Summary. Mesovelia mulsanti is found about the margins of ponds 
and pools upon floating vegetation where it feeds upon small organisms 
coming to the surface film from below or that fall upon it. The species 
probably passes the winter as adults that begin ovipositing in the spring. 
They place their eggs in the stems of plants and even in the spongy wood 
of floating logs. There is a succession of generations throughout the 
season, each cycle requiring about 24 days. Winged and wingless forms 
occur together. Besides flying from pool to pool, they may be transferred 
in the egg stage. Mr. Beamer sent them from the southern part of the 
state to the writer at Lawrence, Kan., in the stems of sedge used as 
packing for some Naucorids. 
The general distribution of this species, and the ease-with which it may 
be controlled and observed both as to oviposition and to hatching, make it 
a valuable object for studies on many phases of animal behavior. 
Family GERRIDAX. Am. & Serv. 1843. 
Amyot and Serville, Hemip. pp. 1, 410, Groupe Gerrides. 
A. TAXONOMY OF GERRIDA. 
Family Characteristics. Long-limbed bugs that live upon the water. 
The antenne are longer than the head and exposed, 4-segmented. The 
head is shorter than the thorax including the scutellum. The limbs are — 
slender, the tarsi covered by close set pile and the claws of at least — 
the front pair distinctly anteapical with the terminal tarsal segment 
more or less cleft. The hind femora extend beyond the tip of the 
abdomen; the intermediate and hind pairs of legs approximated, very 
distant from front pair; ocelli present, but sometimes very obscure; eyes 
close to the anterior margin of prothorax. Rostrum 4-segmented, first 
and second segments short; tarsi 2-segmented; parts of hemelytra more 
or less confluent, often wingless. 
Historical Review. The name Gerris was so promiscuously used for 
various bugs by the early writers that Stal thought to help matters by 
substituting other names. So many of us have known these bugs as 
Hydrobatide. It may be of interest to note that the name Tipula now in 
