THE WATEE SCAVENGER BEETLES. 247 



Subseries D. TRIMERA CLAVICOBNIA. 



The members of this group have the tarsi all 3-jointed and the 

 ventral segments free. They live either in fungi or feed upon plant 

 liee. The following families of the subseries are represented in the 

 State : 



KEY TO I?<DIANA FAMILIES 01? TRIMEKA CLAVICORNIA. 



a. Wings fringed witli long hairs; abdomen not prolougea and with 6 en- 7 



ventral segments ; antennoe with the basal and apical joints thicker 



than the middle ones, the latter with whorls of long hairs; length 



less than 2 mm. Family XII. Tkichoptebygid^, p. 48.S. 



aa. Wings not fringed. 



6. Tarsi with second Joint dilated; third joint consisting really of two 

 joints, the small true third joint being inserted at the base of the 

 last joint. 

 r. Tar.-ial claws dilated or toothed at base; first ventral segment with 

 eoxal lines ; form usually rounded and convex ; head nearly con- 

 cealed I]y the thorax; last joint of maxillary palpi usually 

 hatchet-shaped ; length less than Kr, nnn. 



Family XVI. (Vxcinellid.'E, p. .'lOiJ. 

 cc. Tarsal claws simple; first ventral without coxal lines; fonn oblong 

 or oval, rarely globose; last joint of maxillary palpi oval or tri- 

 angular ; length less than 0.5 mm. 



Family XVII. Endomychid^, p. ri:i:{. 

 bb. Tarsi with second joint not dibited and without a pseudo fourth 

 joint. 

 tl. Elytra entire; ventral segments nearly eciual ; front coxal cavities 

 rounded, not prolonged on the outer side; length less than 'S mm. 

 Family XXVII. Laturidiid^, p. (i."il. 

 (/(/. Elytra truncate behind, leaving the i)ygidium exposed; ventral seg- 

 ments 1 and 5 longer than the otiiers ; front coxa' small, rounded; 

 length less than 3 mm. Family XXIX. JIo.notomid^, p. (ji;(j. 



Family VI. HYDROPHTLIDyB. 



The Water Scavenger Beetles. 



This family comprises, for the most part, oval or elliptical black- 

 ish beetles, differing from the Dytiscidm in being more convex, in 

 having the antennae ending m a distinct club instead of being iili- 

 form, and in possessing palpi which are usually longer than the an- 

 tennae and are projected forward while swimming, while the an- 

 tennas arc usually eouccaled beneath the head. By the inexperi- 

 enced student the palpi are, therefore, often mistaken for the an- 

 tenna'. 



The name of the family is derived from the genus HydropMlus. 

 a word of Greek origin meaning ' ' a lover of water. ' ' As the name 



