20 Rey. H. Clark on the Dytiscidee 
will be convenient perhaps to retain it for the reception of a section 
of that group: the character upon which it was constructed by 
Erichson is “ pedibus posticis in utroque sexu utrinque ciliatis ;” this 
no doubt would hold good for the species known to him, but in 
others it entirely fails. Aubé, in his ‘Species Général,’ p. 366 
(and in his ‘ Iconographie,’ p. 186), points out as additional sepa- 
rating characters the medial lobe of the mentum, and the rounded 
(not carinated) prosternum: these also fail in species which have 
been since discovered. Lacordaire, in his ‘ Genera des Coléoptéres’ 
(vol. i. p. 425), abandons these characters, and suggests as the only 
differences the more depressed form, and the striation of the elytra. 
Species that I have received from Mr. Bakewell, described in this 
paper, and also Amazonian representatives from Mr. Bates have their 
elytra perfectly simple, and only obscurely punctate ; while a species 
of Agabus in the British Museum (A. latissimus of this paper) is quite 
as much, or even more depressed than any species of Copelatus. If 
the genus is allowed to stand, it will contain (so far as our know- 
ledge extends at present) all species with sulcated or deeply striated 
elytra, and, in addition to these, those species that are both depressed 
and oblong, ovate, or subparallel in form. I have little doubt that 
Col. parvulus of Boisduval (Voyage de l’ Astrolabe, p. 50), registered 
by Aubé as an Agabus, will belong to this section of Copelatus. 
1. C. Australia, n. sp. 
C. oblongo-ovalis, elongatulus, punctato-striatus, niger; capite impunctato, 
inter oculos undique bipustulato, nigro, ad apicem rufo adumbrato ; 
thorace ad latera subrotundato, ad margines undique antice et postice 
depresso et plus minus fortiter punctato, ad medium disci breviter 
canaliculato, lineolis brevissimis punctiformibus veluti acuductis, antice 
sparsis postice numerosis, nigro ad latera subrufulo; elytris sub- 
parallelis sat productis, punctorum seriebus tribus, ad latera et ad 
medium sparsim acuductis, nigris; pedibus antennisque rufo-fuscis vel 
rufis ; ¢corpore subtus nigro. 
Long. corp. 43 lin., lat. 13 lin. 
C. Australie, though closely allied to C. acuductus, supplies several 
points of difference, all of which combined will justify us in register- 
ing it as a distinct species: in the thorax the medial longitudial 
marking is hardly ever absent, though often obsolete ; in C. acuductus 
it is never present: in the elytra of the species before us, the pecu- 
liar line-like markings, which extend in C. acuductus over the whole 
surface, are almost limited to the sides, are found very sparingly near 
the middle, and near the suture are entirely absent: in this species 
three striz-like rows of punctures are manifest, in C. acuductus they 
