2 I 6 COLEOPTERA 



downwards but towards one another ; hence the sensitive ad- 

 hesive surface used during coupling is placed on the side of tlie 

 foot, forming thus a false sole : a remarkable modification other- 

 wise unknown in Insects. They breathe chieliy by means of the 

 very large metathoracic spiracles. 



The larvae (Fig. 99, A) are purely aquatic, and are highly 

 modified for this life, being elongate creatures, with sharp, 

 mandil)les and nine abdominal segments, each segment bearing 

 on each side a tracheal branehia ; these gills assist to some extent 

 in locomotion. The stigmata are quite obsolete, but the terminal 

 segment bears four processes, one pair of wliich may Ije looked (in 

 as cerci, the other as a pair of gills corresponding with the pair 

 on each of the preceding segments. The mandiljles are not 

 suctorial, but, according to Meinert, possess an orifice for the 

 diseharge of the secretion of a mandibular uland. Crvrinidae 

 are chiefiy carnivorous in both the larval and imaginal instars. 

 Fully 300 species are known; they are generally distrilnited, 

 though wanting in most of the islands of the world except those 

 of large size. The finest forms are the Brazilian Enliydriis and 

 the ForrorJiynchns of tropical Asia.^ In Britain we have nine 

 species, eight of Gyriiius, one of Orcctochilus ; the latter form is 

 rarely seen, as it hides during the day, and performs its rapid 

 gyrations at night. 



The Gyrinidae are one of the most distinct of all the families 

 of Coleoptera : by some they are associated in the Adephagous 

 series ; but they have little or no affinity with the other mem- 

 bers thereof. Without them the Adephaga form a natural series 

 of evidently allied families, and we consider it a mistake to force 

 the Gyrinidae therein because an objection is felt h\ many tax- 

 onomists to the maintenance of isolated families. Surely if 

 there are in nature some families allied and others isolated, it is 

 better for us to recognise the fact, though it makes our classifi- 

 cations look less neat and precise, and increases the difficulty of 

 constructing " tables." 



Fam. 12. Hydrophilidae. — Tarsi fire-Joinfrd, ilic fn-st johit 

 in many cases so small as to he scarcely erielent: antennae 

 short, of less than eleven joints, not Jilifonn, hut consistiny of 



^ For classification and monograph of the family, see Regimbart, Ann. Soc. ent. 

 France, 1882, 1883, and 1886. For a catalogue, Severin, Ann. Soc. ent. Belgique, 

 xxxiii. 1889. 



