ADEPHAGA — -HALIPLIDAE 



209 



there is a file on the inside of the wing-cases, and the Insect 

 turns tip the tip of the abdomen and scrapes the file therewith. 

 The Insects are called scj^ueakers in the Covent Garden market, 

 where they are sold. 



Fam. 8. Haliplidae. — Antermae hare, ten -jointed ; meta- 

 sternwn marked hy a transverse line; j^osterior coxae 'prolonged 

 as plates, covering a large 

 part of the loiver surface 

 of the ahdomen ; the 

 slender, hut cluhhed, hind 

 femora move hetween these 

 plates and the ahdomen. 

 The Haliplidae are 

 aquatic, and are all small, 

 not exceeding four or five 

 millimetres in length. 

 The ventral plates are 

 peculiar to the Insects of 

 this family, but their func- 

 tion is not known. The 

 larvae are remarkable on 

 account of the fleshy pro- 

 cesses disposed on their 

 bodies ; but they exhibit 

 considerable variety in 

 this respect ; their man- 

 dibles are grooved so that 

 they suck their prey. In 

 the larva of Halipliis, 

 according to Schiodte, 

 there are eight pairs of 

 abdominal spiracles, Ijut 

 in Cnemidotus (Fig. 95, 

 B), there are no spiracles, 

 and air is obtained by 

 means of a trachea traversing each of the long filaments. The 

 Insects of these two genera are so similar in the imaginal instar 

 that it is well worthy of note that their larvae should be distin- 

 guished by such important characters. Haliplidae is a small 

 family consisting of three genera, having about 100 species; 



VOL. VI p 



Fig. 95. — Cnemidotus caesKs. England. A, Imago ; 

 B, larva, highly magnified. (After Schiiidte.) 



