COLEOPTERA POLYMORPHA. 731 



can be folded back into grooves on the tibiae, and all the legs closely pressed 

 against the body. These Pill-beetles are round and very convex. They 

 live amongst moss, or in running water, etc., and feed on sap. The 

 larvae are soft except for the prothorax and last two abdominal 

 segments which are strongly chitinized. The Pill-beetle Byrrhus pilula 

 is common in Britain. The family is small and cosmopolitan. 



Fam. 45. Cyathoceridae. Tarsi not segmented. Antennae four- 

 segmented. The only species of this family is the Central American 

 Cyathocerus horni, a minute, broad beetle. 



Fam. 46. Georyssidae. Tarsi four-segmented. Antennae clubbed 

 and short. Prosternum small. Front coxae exserted but separated. 

 Minute beetles of which only some twenty-five species are known. 

 Georyssus is British ; it lives in wet places and covers itself with mud. 



Fam. 47. Heteroceridae. Eleven-segmented short antennae with the 

 last seven segments broad and forming a toothed club. Four-segmented 

 tarsi. Legs adapted for digging. This family has but one genus, 

 Heterocerus. It lives in burrows on the edges of ponds and streams. 

 By rubbing their third pair of femora on the first abdominal sternum 

 the beetles produce a shrill noise. They are most abundant in the nor- 

 thern temperate zone. Seven species are British. 



Fam. 48. Parnidae. Five-segmented tarsi, last segment elongate. 

 Head usually hidden beneath pronotum. The 

 prosternum projects backward and is received into a 

 groove on the mesosternum. Not a large family of 

 small, aquatic beetles found all over the world. 

 Parnus is European, Psephenus American. 



Fam. 49. Derodontidae. Five-segmented tarsi, 

 fourth segment slender and small. Anterior coxae 

 prominent and transversely extended. A family of 

 very few species divided between the genera Dero- 

 dontua and Peltasticta of the Holarctic Region. 



Fam. 50. Cioidae. Four-segmented tarsi. An- 

 tennae clubbed, short. Anterior and middle coxae 

 small and deeply embedded. Small or minute beetles 

 which browse on fungi, especially on those infesting 



timber. Cis. Fia. 465. "Biscuit- 



_, , . ... _, . , T weevil. Anobium 



Fam. 51. Sphindidae. Tarsi five-segmented. In paniceum. From, 

 other respects this family resembles the Cioidae, Sharp, 

 and like its members these beetles live on fungi which attack timber. 

 Sphindus and Aspidiphorus are British. 



Fam. 52. Bostrichidae. Tarsi five-segmented, the first segment very 

 short. Anterior coxae conspicuous but not in contact. The beetles of 

 this family live in wood and do much damage in forests. The larvae have 

 a swollen thorax and the end of the abdomen is turned forward ventrally. 

 Fam. 53. Ptinidae. Tarsi five-segmented, first segment often larger 

 than second. Anterior coxae small. Pronotum covers head, prosternum. 

 short. This is a large family of small oblong beetles with thick integu- 

 ments. They live in organic matter : the " death-watch," Anobium 

 striatum (p. 723) bores in furniture both as a larva and as an imago. 

 As a rule the beetle present in " weevily " biscuits is A. paniceum (Fig. 

 465), and others bore in books, compressed meat, opium, etc. The larvae 

 are curved, white grubs like miniature cock-chafer larvae. The family 

 is widely distributed. 



