438 



COLEOPTERA. 



seize their food hy throwing their heads buck a,nd extending 

 the jfiws: The larva of the European //. piceus Linn. (Fig. 

 382) matures in two months, then ascends to the bank, forms 

 an oval cocoon, and transforms to a beetle in about forty days. 

 In the genus Sj^erchopsis (S. tessellatus Mels.) the middle and 

 hind tarsal joints are equal in length. Ilydropliilus is large, 

 oval, olive-black and with smooth elytra. In the larva the 

 lateral appendages of the abdomen are soft, flexible, ciliated, 

 and assist in buoj'ing up the heavy, fleshy bod}' (for wdiich 

 purpose the antennae are ciliated) but they do not serve for 

 respiration as iu Berosus, another extensive genus of this 

 family. (SeluiJdte,) H. triangularis Say is a large, pitchy 

 black species. In Hydrohius the last joint of the maxillary 

 palpi is longer than the preceding. Spha^'idium and its allies 

 are characterized by an ovate, convex or hemispherical form, 

 Avith ten rows of punctures or strii«, though in Gydonotum 

 there are no striae. In Cercyon the mesosternum is not pro- 

 duced, and the prosternum is keeled over. "In the larvte of 

 Cercyon and Sphceridium, which represent the Il3'drophilino 

 type modified for life on dry land (thougli in humid places), 

 we find neither lateral abdominal appen- 

 dages, nor even true feet, the animal wrig- 

 gling its way through tlie debris amongst 

 which it lives, whilst the last abdominal 

 segment is the largest of all and is often 

 armed with hooks." (Schiodte.) 



Platypsyllid^ Leconte. The only spe- 

 cies of this family known is a small brown 

 insect, -16 inch long {^PlatypsyUa castoris 

 Ritsema, Fig. 382\ enlarged), found on 

 the American beaver. The body is broad, ^'S- 2^■^'• 



flattened, eyeless, with short elj'tra, and spiny on the legs and 

 salient parts of the body, as in the flea. Leconte remarks that 

 its affinities are "very composite, but all in the direction of the 

 Adephagous and Clavicorn series, though chiefly with the latter.' 



SiLPMiO/E Leach. The Carrion or Sexton beetles are useful 

 in burying decaying bodies, in which they lay their eggs. 



