402 Rev. H. Clark cm the Dytiscidee 



from H. gibbus in its almost concolorous elytra, in the punctation 

 of the thorax, and in its larger size. 



A single example is in the cabinet of Mr. Bakewell, received by 

 him from Adelaide. 



4. H. gibbus, n. sp. 



H. latus, ad medium subparallelus, punctato-striatus, fuscus aut fusco 

 lunbratus aut flavus ; thorace transverse ad basin fortiter depresso et 

 punctato ; elytris ad humeros latis et rotundatis, punctato-striatis, striis 

 vel tenuiter vel late fuscatis ; pedibus antennisque flavis. 



Long. corp. 1| lin., lat. f lin. 



Broad, robust, subparallel, in colour varying from pale flavous to 

 fuscous : head elongate in front, at the base obscurely punctate : thorax 

 transverse, the sides being rectilinear, and considerably constricted in 

 front ; the surface at the base is broadly and deeply marked by a trans- 

 verse depression, which, when viewed laterally, gives prominence to the 

 anterior disk ; the surface is sparingly punctate, more distinctly near 

 the line of the base ; this punctation varies in different examples, as 

 does also the coloration, which sometimes is pale flavous, sometimes 

 clouded with fulvous, and sometimes dark fuscous : elytra robust, the 

 shoulders being broader than, and forming a distinct angle with, the 

 sides of the thorax ; ten striae are formed by fuscous lines, in-the midst 

 of these lines are series of regular punctures ; these lines of fuscous 

 colour vary in breadth, in some examples being hardly broader than 

 the punctures, in others obfuscating almost the whole surface, thus 

 causing the colouring of the elytra to vary in different examples, some- 

 times being flavous with narrow fuscous lines, and sometimes entirely 

 fuscous : legs and antennae flavous. 



The remarkable thoracic depression in this species separates it 

 from all other species of the genus with which I am acquainted, 

 except the preceding : from H. fuscatus the species may be distin- 

 guished by its smaller size, as well as by the greater depth and 

 breadth of the punctures of the elytra. 



This variable species is found in the neighbourhood of Moreton 

 Bay. In the cabinets of the British Museum, Mr. Bakewell, and the 

 llev. H. Clark. 



Tribe II. Pelobiid^;. 



Genus Pelobius, Schonherr. 



1. P. Australasia 1 ., n. sp. 

 P. ovatus, tenuiter et crebre punctatus, flavo-ferrugineus, infra niger, 



capite nigra ; thorace lato ; elytris latis, confertim subfusco punctatis ; 



pedibus antennisque flavis. 

 Lung. corp. 5 lin., lat. 2 J lin. 



