220 HYDROPHiLiD^. \_Mydrophihis. 



uncommon in many places near London, in stagnant water ; Sheerness, Lee, Wands- 

 worth, Croydon, Duhvich, Camberwell, Belvedere, Chelsea, Hampstead, Eppiug Forest, 

 &c. ; Whittlesea Mere and Yaxley Feu ; Swansea ; formerly recorded by Mr. Dale 

 from Glanville's Wootton, Dorset. 



The larva of this insect is figured by Westwood (CLissif., vol. i. , p. 121, 8, 11): 

 when full growu it is three inches long, of a somewhat conical form, and stouter than 

 the larvaj of the Dytiscidaj ; the head is reddish brown, horny, and almost circular, 

 with strong mandibles, the lower surface being convex and the upper flattened ; the 

 body is terminated by two short cerci, which are employed in respiration ; these larvae 

 are very voracious, and feed on small molluscs, which they break upon their backs ; 

 they are able from the peculiar formation of their heads to twist them back so fiir as 

 to allow of their thus using their backs for a table, as has been noted by Lyonnet, 

 ]Mulsant, and other observers : the females, as noted above, construct a cocoon for 

 their eggs, which batch in from a fortnight to six weeks, and in a few hours thelarvEe 

 leave their shelter ; when full growu they Cjuit the water and form an oval cell iu the 

 adjacent bank, where they change into a thick oval pupa fi-om which the perfect insect 

 emerges in about forty days, the whole period occupied from the hatching of the e^g 

 being about one hundred days ; Stephens says that the larva changes to a pupa 

 beneath dung, making a deep hole for the purpose, but 1 have not seen this fact cou- 

 firmed by other authors. 



HYDROCKARIS, Latreillc. 



{Hydrox>liilus, Leacli. Hydrous, Brulle.) 



This genus comes very near the preceding but its members arc always 

 of a much smaller size : it comprises about twenty species, which are 

 widely distributed over the surface of the globe (Siberia, Ceylon, Java, 

 Brazil, &c.) ; like the Ilydrophili they are found in stagnant water. 



H. caraboides, L. Oblong oval, upper surface olive-black, some- 

 times with a greenish reflection, shining ; maxillary palpi and antennae 

 except club reddish ; thorax rather short, with two short rows of large 

 punctures on each side of middle in front ; elytra somewhat wider 

 behind with very superficial stripe, the third and fifth interstices with 

 regular rows of large punctures, which are less regular on the seventh, 

 ninth, and tenth ; legs blackish, the anterior pair sometimes lighter ; 

 abdomen pubescent with a small smooth shining space at apex, the 

 segments with indistinct yellow markings on margins ; male with the 

 claws of anterior tarsi sharply bent like a grappling-hook. Long. 14-18, 

 lat. 6^-8 mm. 



Like the preceding, local but not uncommon in the London district, but found iu 

 very few other localities ; Lee, Wandsworth, Barnes, Dulwich, Epping ; Waltham- 

 stow, Essex ; Askham Bog, York ; Swansea ; formerly recorded from Whittlesea 

 Mere and the neighbourhood of Cambridge. 



The larva of this insect is figured by Westwood (Classification, i. 121, 8, 13), and 

 by Schiodte (i., PI. iv., Fig. 1), who also figures the pupa (Fig. 4) : the larva is slate- 

 coloured with the scuta fuscous; the head is larger and squarer than iu the larva of 

 Hydrophilus, broadest in front, and narrowed behind ; the scutum of the prothorax 

 is complete, of the meso- and meta-thorax incomplete ; the scuta of the dorsal abdominal 

 segments are broken up, and on each segment take the form of four small cylindrical 

 corneous excrescences pointing downwards; the larva is chiefly remarkable for these 

 and for the long ciliated appendages (something like those iu Gyrinus) borne by the 



