Coleoptera. 31 



Metasternum without an antecoxal sclerite 6 



4. Antennje eleven-jointed; hind coxie movable and simple; terrestrial 5 



Antennae ten-jointed; hind coxse fixed, expanded so as almost to conceal the 



base of the abdomen (PI. 4, fig. 124); small water beetles. (Cnemiddtus, 

 Haliplus.) HALIPLID^ 



5. Antennae inserted on the front, above the base of the mandibles; eyes promi- 



nent; head vertical, wider than the thorax. Tiger-beetles. (Cicindela, 



Omus, Tetracha.) CICINDELID-^ 



Antennae inserted on the sides of the head, between the base of the mandibles 

 and the eyes; head usually held horizontally and generally narrower than 

 the thorax. Ground beetles. (Omophron, Calosoma [Caterpillar-hunter], 

 Bembidium, Platynus, Brachinus [Bombadier beetle], Pterostichus, Har- 

 palus, Chlaenius) (PI. 5, fig. 97; PI. 6, fig. 108; PI. 7, figs. 158, 164). 



CARABID^ 



6. Metasternum prolonged behind as a triangular process; aquatic 7 



Metasternum not prolonged between the coxae; scutelium absent; antennae 



formed like a string of beads; rare bark beetles. (Rhysddes) (PI. 7, fig. 146.) 



RHYSODID^ 



7. Antennae slender, abdomen with six segments; eyes two. Diving beetles. 



Water-tigers. (Dytiscus, Cybfster, Acilius, Agabus, Colymbetes) (PI. 5 



fig- 101) DYTISCIDiE 



Antenna; short, abdomen with seven segments; eyes four. Whirligig beetles. 

 (Gyrinus, Dineutes) (PI. 6, fig. 117; PI. 7, fig. 147) GYRINED^ 



8. Antennae clubbed or not, if clubbed, not lamellate 9 



Antennae with the last three to seven joints enlarged on one side to form a comb- 

 like or lamellate club which can often be opened and closed (PI. 7, figs. 

 149, 150, 151); legs often fitted for digging; tarsi almost always five-jointed, 

 front tarsi of some dung beetles may be absent; larvae with thick curved 

 body and well-developed legs. (Lamellicornia.) 114 



9. Head not prolonged into a beak; palpi flexible, gular sutures double, at least 



before and behind; prosternal sutures distinct, proepimera not meeting 



behind the prosternum 10 



Head generally prolonged and snout-like (PI. 6, fig. 125), palpi nearly always 

 rigid; gular sutures confluent medially; proepimera united behind the pro- 

 sternum, prosternal sutures wanting, antennae often elbowed; fourth tarsal 

 joint usually indistinct; larvae legless or with short legs. (Rhynchophora.) 110 



10. Fourth and fifth tarsal joints not immovably united, the articulation between 



them like those between the other joints (PI. 7, figs, 143, 168) (If rarely 



immovably united as in some Erotylidae, the antennae are clavate) 11 



Fourth tarsal joint minute, fused with the fifth; tarsi usually densely pubes- 

 cent below, the first three joints dilated and with a sole, the third joint 

 usually bilobed (PI. 7, figs. 157, 167); antennae thread-like, rarely serrate or 

 thickened apically; plant feeders. (Phytophaga.) 108 



11. Hind tarsi with at least as many joints as the others 12 



Hind tarsi four-jointed, front and middle tarsi five-jointed. (Heter6mera.) 86 



