196 



Usinger: Hemiptera 



— Pronotum and hemelytxa heavily rastrate (fig. 7:9p); 



widely distributed, North America 



vulgaris (Hungerford) 1925 



Key to California Species of Callicorixa 



1. First tarsal segment of hind leg infuscated for at least 

 a part of its length (figs. 7:5d; 7:9s); western North 

 America, Alaska to California .. . vulnerata (Uhler) 1861 



— First tarsal segment of hind leg concolorous throughout 

 (fig. 7:9r); northern United States, Alaska and Canada. 

 Sierra Nevada, California audeni Hungerford 1928 



Key to California Species of Slgara 

 (Subgenus Vermicorixa Walton) 



1. Metaxyphus short, plainly broader than long 2 



— Metaxyphus about as broad as long 6 



2. Ostiole almost in lateral bend of mesoepimeron, and 

 connected to metasternum by the broad, often dark 

 post-coxal piece (fig. 7:9Z); widespread, northern United 

 States and Canada. Mammoth Lakes, California 



grossolineata Hungerford 194 8 



— Ostiole not in lateral bend of mesoepimeron, closer to 

 tip of mesoepimeron 3 



3. Anterolateral third of clavus ridged and projecting 

 laterally over pruinose area along claval suture (fig. 

 7:9m); Washington and California, mouth of Van Duzen 

 River vandykei Hungerford 1948 



— Anterolateral margin of clavus not as above 4 



4. Mesoepimeron of equal width from ostiole to lateral 

 bend; ostiole posterior to distolateral angle of meso- 

 sternum; North America, widely distributed, California, 

 Yuba County (fig. 7:9n) alternata (Say) 1825 



— Mesoepimeron broader at lateral bend than at level of 

 scent gland ostiole; ostiole on a level with distolateral 

 angle of mesosternum 5 



5. Right clasper of male genital capsule roundly elbowed, 

 slightly widened apically, abruptly rounded, and minute- 

 ly produced at tip; pronotal disc of female more than 

 half as long as broad (figs. 7:5<z; 7:9/); California 

 coast mckinstryi Hungerford 1948 



— Right clasper of male genital capsule angulately 

 elbowed, tapering apically with the tip subacute and 

 bent; pronotal disc of female less than half as long as 

 broad; western United States, widespread in California 

 washingtonensis Hungerford 1948 



6. Male pala broadest near its base, an oblique ridge 

 across palar face (fig. 7:9i); lateral margin of pronotal 

 disc acute; Nevada, Utah, Wyoming 



nevadensis (Walley) 1936 



— Male pala broadest beyond middle, no ridge across 

 palar face; lateral margin of pronotal disc rounded; 

 western United States, northern and central California 

 (fig. 7:9A) omani (Hungerford) 1930 



Key to California Species of Cenocorlxa 



1. Male pala with peg row divided (fig. 7:9z); western and 

 northern United States, Sierran California 



bifida (Hungerford) 1926 



— Male pala with peg row variously curved but not divided 



2 



2. Last segment of hind tarsus deeply embrowned for its 

 entire length (fig. 7:9cc); California and Utah, Sierra 

 and Wasatch Mountains kuiterti Hungerford 1948 



— Hind tarsi concolorous throughout, or with only the tip 

 of last segment embrowned 3 



3. Male pala with peg row doubly curved (f ig. 7:9aW); 

 strigil very small, of about 5 regular combs; western 

 United States wileyae (Hungerford) 1926 



— Male pala with peg row not doubly curved; strigil larger, 

 with 10 or more combs 4 



4. Right genital clasper of male bifurcate at tip; inter- 

 ocular space greater than width of an eye (fig. 7:9aa)- 

 western and central United States, Sierran California 



utahensis (Hungerford) 1925 



— Right genital clasper of male not bifurcate at tip; inter- 

 ocular space equal to or slightly less than width of an 

 eye 5 



5. Interocular space slightly narrower than an eye; right 

 genital clasper of male narrowed beyond subapical bend 

 (fig. 7:9y); Oregon, Washington 



andersoni Hungerford 1948 



— Interocular space equal to width of an eye; right genital 

 clasper of male widened beyond subapical bend and 

 then slightly narrowed to broad apex (fig. 7:966); 

 California coastal and Modoc County 



blaisdelli (Hungerford) 1930 



REFERENCES 



ANCONA, L. 



1933. El Ahuatle de Texcoco. Ann. Inst. Biol., 4:51-69. 

 FORBES, S. A. 



1878. Breeding habits of Corixa. Amer. Nat., 12:820. 

 1888. On the food relations of freshwater fishes: a sum- 

 mary and discussion. Bull. Illinois Lab. Nat. Hist., 

 2:475-538. 

 GRIFFITH, M. E. 



1945. The environment, life history and structure of the 

 water boatman, Ramp ho corixa acuminata (Uhler). Univ. 

 Kansas Sci. Bull., 30:241-365. 

 HUNGERFORD, H. B. 



1948a. The Corixidae of the Western Hemisphere. Univ. 

 ' Kansas Sci. Bull., 32:1-827. 



19486. The eggs of Corixidae. Jour. Kansas Ent. Soc, 

 21:141-146. 

 HUTCHINSON, G. E. 



1931. On the occurrence of Trichocorixa Kirkaldy in 

 salt water and its zoo-geographical significance. 

 Amer. Nat., 65:573-574. 

 POPHAM, E. J. 



1941. The variation in the colour of certain species of 

 Arctocorisa and its significance. Proc. Zool. Soc, 

 Lond. (A), 111:135-172. 



Family NOTONECTIDAE 



Back Swimmers 



Back swimmers are a characteristic feature of pond 

 life in most parts of the world. They are fierce pred- 

 ators, attacking any invertebrate of appropriate size 

 and even relatively larger fish fry. The common name 

 is derived from the unique habit of rowing with the 

 ventral (in a morphological sense) side uppermost. 

 In body form they are long and slender, deep bodied, 

 and convex dorsally. Ocelli are absent. The antennae 

 are short, partly concealed, and of three or four seg- 

 ments. The rostrum is short, stout, and four-segmented. 

 The front and middle legs are adapted for grasping 

 prey or for holding on to objects in the water. The 

 hind legs are very long, oarlike, and fringed with 

 long swimming hairs. The adult tarsi in our species 

 are two-segmented, with two claws present but incon- 

 spicuous on hind legs. The abdominal venter is 

 longitudinally keeled at the middle with long hairs 

 which, together with the inwardly directed hairs on 

 the sides of the venter, close over two troughs which 

 form air chambers. 



Relationships. — Notonectids are commonly grouped 



