African Species of Erotylide. 141 
sexual dimorphism of some at least of the species. The 
males are .characterised by greatly dilated tarsi; but, in 
several species, they have a more remarkable peculiarity 
in a conspicuous opaque area upon the posterior part of the 
elytra. Analogy would lead us to consider this distinctive 
of the females, as in Water-beetles, various Lamellicornia, 
and other groups in which a similar phenomenon occurs ; 
but this is not the case, The dilated tarsi are not by them- 
selves sufficient to determine the sex, for, although almost 
invariably indicative of the male, in certain genera of 
Languriing, a closely related group, it is the female in which 
the tarsi are most dilated. In these and other cases the 
determination of the sex from external indications only has 
led to totally wrong conclusions, and dissection is essential 
to absolute certainty. 
As is frequently found -with secondary sexual characters, 
the opaque dorsal area is not found in all the species of the 
genus. I have found it in three, in one only of which 
(P. andree, Crotch) both sexes are known, but in all it is 
confined to male specimens. In P. coccinelloides, Crotch, 
P. dorsalis, Gorh., and P. bizonatus, sp. n., both sexes are 
equally smooth. Although it has not hitherto been recorded, 
this curious phenomenon is also found in the genus Neo- 
triplae—in a strongly marked form in N. atrata, Lewis, and 
to a less extent in N. lewisi, Crotch, both Japanese species. 
Dacne (Engis) equinoctialis, Thoms., is almost certainly 
the species later described by Crotch as D. capensis, which 
has an exceedingly wide range in Africa. 
The only known African representatives of the Encaustes 
group.are here described. Gorham described in 1883 
a species, Micrencaustes torquata, the habitat of which 
he stated to be Old Calabar ; but in 1901 he expressed 
himself doubtful of its African’ origin. In the British 
Museum there is a specimen of this “species, derived, like 
Gorham’s type, from Andrew Murray’s collection, and 
labelled “ Malay Peninsula.” 
The true systematic position of this group has never been 
recognized, The monographer of the Erotylidze, Lacordaire, 
in his Synopsis of the genera, divided them into two series, 
at the head of each of which he placed an isolated genus as 
to the actual affinities of which he was evidently uncertain. 
The first of these, Hncaustes, on account of its large size and 
elongate shape, is, not unnaturally, generally associated 
- with the other large Old World species represented by those 
now called by M. Bedel Mimodacne ; but Chapuis has 
pointed out that Lacordaire, in adopting this view, was 
