41 6 Introduction to Animal Morphology. 



often metallic in lustre ; antennae thread-like, eleven-jointed ; 

 mandible sharply curved ; intestine with two anal glands, 

 whose secretions contain butyric acid. Brachinus crepitans, 

 the bombardier beetle, expels this forcibly, together with air, 

 when disturbed. The elytroe are sometimes connate. An- 

 ophthalmus, a cavern form, is blind. The larvae are long, 

 sometimes hairy. Procerus includes the largest known spe- 

 cies. 21. Cicindelidae — slender, often lively-coloured, spot- 

 ted, or bald ; head broader than neck ; maxillary palps with 

 terminal hooks ; larvae linear, with broad head and prothorax ; 

 often with the eighth ring broader and higher than the others, 

 and with two fleshy dorsal processes. 22. Amphizoidae — hairy ; 

 the fore-limbs gressorial ; the costaeofthe hind-limbs approxi- 

 mated, flattened, as in the next family ; outer edge of the 

 maxilla with an unjointed process. 23. Dyticidas — flat, aqua- 

 tic, oval, with thread-like, eleven-jointed antennae : hind-legs 

 flat, oar-like ; the neck has lateral odoriferous glands. The 

 intestine has an appended csecal sac, with many transverse 

 folds. In swimming, the hind legs move simultaneously 

 (Dyticus, &c.), or alternately (Pelobius). 24. Gyrinidse — 

 eyes divided by the edge of the head into an upper and 

 lower series; antennae short; hind-leg short, fin-like; they 

 swim in circles, and fly as the last ; larvas centipede-like, 

 with lateral abdominal appendages, and mouth as last. 

 Some are marine as well as fresh water. 25. Hydrophi- 

 lidae — oval or semi-circular, with broad swimming hind- 

 feet ; antennae six- (Sperchus) nine-jointed (Hydrophi- 

 lus, Hydrobius) ; club-shaped ; palps as long as antennae. 

 These beetles are recommended by Professor Klein as the 

 best animals wherein to trace the structure of muscular 

 fibres, and nerve endings therein. 26. Staphylinidae (Brache- 

 lytra) — body long ; elytrae short ; hind-wing folded ; antennae 

 lo-i I -jointed ; males sometimes heteromerous ; larvae like the 

 perfect insect, with two hinder bristles to the abdomen, and 

 a tubular anus ; stomach, villous internally, preceded by a pro- 

 ventricle with chitinous ridges. 27. Paussidae — antennae 2-10- 

 jointed, clavate ; head trigonal ; tarsus four-jointed ; elytra 

 long four-angled, with a fold at the outer angle ; ventral rings 

 four. 28. Hysteridae — antennae retractile, short, bent, the 



