Hydrobius.^ nYDRoriiiLiD.T;. 223 



lar;^for, longer in proportion, and more ofton sliowinj^ a motalHc roflcctioii ; 

 it is easily (listingiiislied by the absence of stricC on the elytra, and by the 

 fact that the posterior femora are quite smooth. L, 8-9 mm. 



Brackish ditches ; local, but not uncommon in some districts near London, and in 

 tlio south and south-east of England, (iraveseiid, Sht'orncss, Whitslablo, Kainhani, 

 Di'al, Hastings, &c. ; Soutbport and Lancaster (Mr. Reston) ; according to M. Bedel 

 this insect possesses a slight power of stridulatiou. 



PHZI.HVDRUS, Solier. 



This genus comprises about fifty species, which are widely distributed 

 both in the northern and southern hemispheres, from Northern Europe 

 and America to Ceylon, Java, Chili, and Brazil ; they are found in 

 stagnant water, and some of the species are confined to brackish ponds 

 and ditches. 



The larva; of this genus closely resemble those of Ilelocharos ; the females, however, 

 do not carry their egg-sac underneath the abdomen, but attach about fift(!en little 

 triangular silky packets to the Leiiuia on the surface of the water, each containing 

 ten or a dozen eggs ; the larviC do not leave these receptacles for two or three days 

 after they have hatched. 



Six of the seven European species are found in Britain, and may be 

 distinguished as follows : — 



L Thorax with more or less distinct larger punctures ar- 

 ranged transversely on middle of sides ; size larger, 

 i. Maxillary palpi with second joint dark .... P. TESTACEUS, F. 

 ii. Maxillary palpi with second joint entirely testa- 

 ceous. 



1. Head testaceous, sometimes darker in mid<llo . P. maritimus, Thorns. 



2. Head black, at all events as far as anterior margin 



of eyes. 

 A. Elytra without a trace of series of larger 

 punctures ; last joint of maxillary palpi testa- 

 ceous (at most very slightly darker at extreme 



apex) P. NIGRICANS, Ziff. 



IJ. Elytra with indistinct traces of series of 

 larger punctures ; last joint of maxillary palpi 



rather broadly l)lack at apex P. MELAXOCEriiAl.us, 01. 



IL Thorax without larger punctures at sides ; size 

 smaller. 

 i. Head without yellow spots in front of eyes ; last 



joint of maxillary palpi black at apex P. minutus, F. 



ii. Head with distinct yellow spots in front of eyes j 



last joint of maxillai-y palpi entirely testaceous . . P. COAKCTATUSj GreiU. 



P. testaceus, F. Oblong-ovate, ratlier conve.v, upper surface 

 finely and closely punctured, ligliter or darker testaceous, head black as 

 far as front of eyes, disc of thorax dusky ; elytra Avith a sutural stria 

 reaching from apex to a little bcynnd mid<lle ; legs ferruginous. 

 Ii. 6-7 mm. 



Ponds and ditches ; local but not uncommon ; London district generally ; Norwich ; 

 Deal; Hastings; liamsgatc; Horning Fen; Swansea; Devonshire; Manchester 



