116 THE UNIVERSITY SCIENCE BULLETIN. 
KEY TO RHEUMATOBATES. 
Taken from Bueno’s Gerrids of Atlantic States.* 
sl 
A. Hind femora and coxe of male curiously swollen and distorted. — 
Female with mesosternum unicolorous. R. rileyi Bergr. 
AA. Hind femora and coxe of male not swollen and distorted. Female 
with mesosternum yellow with the anterior margin and the two — 
posterior diverging bands brownish-black, these bands not reaching ~ 
to the posterior wane and dilated near the anterior margin. 
R. tenuipes Meinert. 
Genus HALOBATES Eschs. 
“Head triangular; eyes, globular; beak, short and stout. Fourth seg- 
ment of antenneze longer than the third. Mesothorax very large; abdo- 
men, short and conical; front legs, short and femora thickened some- — 
what. Middle legs, very long and slender. The hind legs shorter than ~ 
the middle ones. Found upon the floating mats of seaweed often far at 
sea. The two species reported from our land were described by Esch- | 
scholtz in 1822. The descriptions here given are from Burmeister’s — 
Handbuch.” 
Halobates sericeus Eschs. 
Eschscholtz, Entomographien, p. 108, 1822; Burmeister, Handb. d. Ent. II, p. 209, 1835. 
“Corpore ovali, subtus argenteo, supra albo-cinereo; oculis flavis. 
Monee. 
Locality: Florida. 
Halobates micans Eschs. 
Eschscholtz, Entomographien, p. 107, 1822; Burmeister, Handb. d. Ent. II, p. 208, 1835. — 
“Corpore conico, subtus argenteo, supra cinereo, zneo, miconte; oculis © 
atris. Long., 1%4'”.” 
Locality: California. 
B. BIoLOGY OF THE GERRIDA. 
General Notes. The water striders are to be noted everywhere. 
Bueno says “their haunts range from living springs, clear, secluded, 
shady, and cool, to the vast expanse of the tropic ocean steaming under a 
torrid sun, or dashed by wild storms into mighty waves.” So far as we 
know them, the fresh water forms place their elongate white eggs upon — 
supports at the water’s surface. They feed upon organisms nurtured in 
the water, or upon plants about the shore. They also prey upon flounder- 
ing insects that chance to tumble into the water. Bueno and Drake have 
given us life history notes upon the group and Essenberg has studied the 
behavior of some of them. . 
Genus GERRIS Fabr. 
For this country we have life history notes by Bueno upon G. mar- 
ginatus and G, remigis, and by Drake upon G. conformis. The writer has 
studied the first two in Kansas. 
Gerris remigis Say. 
Habitat. This large strider is usually apterous and more often found 
on running water, or pools connected therewith, than on isolated small 
ponds. They are gregarious fellows, seeking a resting place in the shade 
HED over apeine bank or bush, but taking wildly to the open when alarmed. 
UN third species R. trulliger, Bergr. is described in Bul. Brookl. Ent. Soc. p.. 63, 
1915. My manuscript for this genus has been misplaced. Bergroth has a aoe at papey 
in Ohio Naturalist, vol. VIII, p. 381. 
