Dr. Malcolm Burr’s Revision of the Genus Diplatys. 23 
In the next type, which we may call the sloping type, 
the frons is distinctly tumid, the tumidity gradually 
dying out posteriorly, ending at the posterior margin 
of the head itself; the occiput is not strongly nor 
abruptly depressed, nor markedly separated from the 
frons, the transverse suture being obsolete, and the median 
suture nearly so. In this type there are more or less 
sharp keels running from the interior margin of the eye 
to the extero-posterior angles of the head: these keels are 
gently arched in D. lefroyi; in D. aethiops, D. gansoni, and 
D. severa they are strong, and the posterior margin is 
incrassate, so that they fuse with it, thus forming a blunt 
rectangular ridge at the posterior angle, this ridge con- 
tinuing to the median suture, which is short and distinct ; 
in D. jacobsoni the keels are sharp and distinct, but short, 
whereas in D. gerstaeckert and D. ernesti they are longer. 
In the third type of head the frons is markedly tumid 
and the occiput strongly depressed ; the transverse suture 
is sometimes strongly marked, but sometimes indistinct 
or obsolete, the tumid frons passing abruptly into the 
depressed occiput with no clear suture, but only brusque 
change from tumidity to depression. The members of 
this group, which have rather short and feeble keels, are 
D. siva, D. annandalei, D. conradti, D. angustatus, and D. 
grifithst ; those with strong, sharp, and long keels, are 
D. macrocephala, D. bormansi, D. greeni, D. rufescens, D. 
vorselert, D. raffrayi, D. gracilis, and D. fletcheri. The 
sutures are especially distinct in D. vosselert. 
There appears, however, to be no connection between 
the structure of the head and geographical distribution, 
since we find in each group this arranged species from 
various zoogeographical regions. 
In order, therefore, to approach a more natural system, 
it is necessary to adopt the structure of the apex of the 
abdomen and its appendages as our basis of classification, 
having recourse to the structure of the head and form of 
the pronotum for supplementary features. 
The pronotum is long and narrow in JD. thoracicus, 
but as a rule the length is but little greater than the 
breadth: the usual outline ranges between subpentagonal, 
subrectangular, and suboval. 
In some species the abdomen is strongly and abruptly 
dilated at the apex, the last segment being strongly 
inflated ; in others, the abdomen is less strongly and more 
