38 



WHIRLIGIG BEETLES. 



certainly does occur in such situations as ditches, in salt marshes, 

 and I suppose was first found in a locality of this description and 

 named accordingly, G. bicoloi\ however, is peculiar to marine 

 situations, I have taken it in ditches near the sea at Weymouth, 

 but I should never have expected to meet with it in the Bath 

 canal. But there can be no doubt as to my specimen being G. 

 bicolo}% from the elongated shape and nearly parallel sides of the 

 elytra. Another species, G. distindus, I have taken from ditches 

 at Bournemouth and there only. 



I do not notice any sexual difference other than the punctura- 

 tion which I have already alluded to. I find no trace of the 

 enlargement of the anterior tarsus of the male, which is very 

 striking and interesting in the Dytiscidce. When touched or irri- 

 tated, they emit a milky fluid of a disagreeable odour, which is 

 discharged from the pores of different parts of the body, or, 

 according to De Geer, from the minute retractile lobes at its 

 extremity. It is stated that G. miniitus and G. villosus are scent- 

 less. I do not know if this is so, as I have never taken either of 

 these two insects. The membraneous wings are very large for the 

 size of the insect, and, owing to the peculiar arrangement of the 

 nervures, fold up in a remarkable manner. 



" The female, shortly after impregnation, deposits her eggs, 

 which are small and of a cyUndrical form, and placed end to end 

 in parallel rows on the leaves of aquatic plants, and from which, 

 at the end of eight days, the larvas are produced. The larva is 

 long, narrow, and depressed, and nearly resembles a small centi- 

 pede, of a dirty white colour, composed of thirteen segments, 

 including the head, separated from each other by lateral incisions. 

 The head is large, oval, and depressed, armed with two strong 

 jaws, two short, filiform, four-jointed antennae, several small tuber- 

 cular eyes (the number of which De Geer could not discover), 

 forming a group on each side of the head, and slender maxillary 

 and labial palpi. The clypeus is deeply notched in front, without 

 any distinctly articulated labrum. To each of the three anterior 

 segments of the body is attached a pair of moderately long and 

 slender legs \ and from each side of each of the eight following 

 segments arises a long, slender, transparent, and membraneous 

 filament, bent rather backwards, and terminating in a point. The 



