158 ADEPHAGA. [Amphizoithe. 



sion to exotic groups, and the question of the position of Amphizoa is 

 especially interesting as bearing upon the position of Pelohius, with 

 which in some points it is rather closely allied, 



PELOBIID^. 



In this family the metasternal episterna do not reach the middle coxal 

 cavity, and in this, as well as in its habits and swimming powers, it 

 differs from the Amjyhizoidie ; it resembles the members of tlie latter 

 family, however, in the fact that the metasternum has a very short and 

 small ante-coxal piece in front of the posterior coxfe, separated by a 

 distinct suture, and not produced between the coxas : in the Carabidae and 

 the Haliplidse this ante-coxal piece is large, and is extended triangularly 

 between the posterior coxa, and the well-marked suture reaches across 

 the body to the episterna ; the Dytiscidaj have no trace of an ante-coxal 

 piece, and liave the metasternum, which is short, pointed between the 

 coxae; the Pelobiidse, therefore, differ from them in this respect, and further 

 in having the extension of the hind coxae, so characteristic of the Dyti- 

 scidae, short and transverse, instead of broad and extending forwards as in 

 the latter family ; the head also is free and not sunk in the prothorax, and 

 the formations of the mentum and mouth parts generally present consider- 

 able points of difference ; moreover, the general contour and appearance 

 is exceedingly unlike that of the Dytiscidae, and although this perhaps 

 is not of much weight, yet in a family where the general resemblance is, 

 with one or two exceptions, very striking, it may be allowed a little more 

 consideration than in ordinary cases. In his work on the Dytiscidae 

 (1. c. p. 258), Dr. Sharp classes the Pelobiidai with the Dytlsci Fragmeyi- 

 tati, but in his paper on the classification of the Ade]ihaga referred to 

 above (1. c. p. 67) he considers that Dr. Horn is justified in isolating 

 them. 



PEZiOBIUS, Schonherr. 



{Hygrohia, Latr. Hydrachna, Fabr.) 



This genus comprises only three species, one of them European, and 

 the others Australian ; our species stridulates very loudly, and has 

 earned in some parts of the country the name of " Screech-beetle." 



The larva of P. tardus is figured by Schiodte, vi., PI. v. 1 and 3, and vi. 1 : it is 

 broadest about middle and convex, of a yellow or luteous colour with darker markings 

 on the bead and dorsal scuta ; the bead is rather broad almost semi-circular, the 

 prothorax very large, trapezoidal, somewhat transverse, the meso- and meta-thorax 

 narrow ; the scuta cover the whole upper surface of the segments ; the abdominal 

 segments are eight, the last being conical and bearing two long setose cerci ; these 

 and the anal appendage are about equal in length, and are each as long as all the 

 abdominal segments together ; the legs are long with double claws of about equal 

 length : a figure of the larva viewed sideways is given by Schiodte (vi. 1) ; in this 

 ))osition it very much resembles a crustacean ; the larva is furnished with branchiie 

 or gills on its under surface ; it lives iu water and is very predaceous. 



p. tardus, Ilerbst. {Htrnianni, F.). Oval, very convex, ferrugi- 



