ENTOMOSTRAGA FROM CEYLON. 131 
The species is remarkable for the strongly asymmetrical ex- 
pansions of the genital segment of the female, and for the modified 
seta of the right furcal branch and recurved lateral spine of the right 
fifth foot of the male. 
ture of the prehensile antenna of the male, make Diaptomus greent 
These characters, combined with the arma- 
a remarkably distinct species. 
If we compare it with the four species of Diaptomus previously 
recorded from Ceylon, viz., D. orientalis, Brady, D. lumholtzi, Sars, 
D. drieschi, Poppe & Mrazek, and D. singalensis, Daday (Table 1), we 
find that, though these four species form a fairly homogeneous group 
themselves, D. greens differs very markedly from all, though approach- 
ing nearest to D. singalensis. Onthe other hand, in the possession 
of a hook on the last joint of the prehensile antenna of the male it 
agrees with D. denticornis, Wierz., D. alluaudi, Guerne & Rich., and 
D. chevreuxi, Guerne & Rich., three 
species. 
“ Circum Mediterranean ”’ 
Tabulating the most important characters of the four 
species (Table 2) one finds a considerable further agreement, parti- 
cularly with regard to the prehensile antenna and the fifth foot of 
the female. The vestigial condition of the third joint of the exopo- 
dite of the latter is common among the North American species of 
Diaptomus, but is otherwise rare. For systematic purposes D. 
greent may, I think, be classed with the above-named species, and 
apart from the four remaining Sinhalese species. 



















TABLE 1. 
| 
D. orientalis./D. lamholtzi.| D. drieschi. |D.singalensis| D. greeni. 
Last segment of} With small | With small | Scarcely With small | With large 
the Cephalo-| wings wings winged wings wings 
thorax. xX @ | 
GenitalSegment — — | — — With wings 
9 | ; 
Ist Antenna of} End of (|End of furca\End of furca'Second abdo-| End of 
@ reaches genital _ minal seg- | Cephalo- 
segment ment thorax 
Last joint of the —. —- a — With hook 
Prehensile an- 
tenna 
Last joint but] With claw | With claw |With a short — — 
two of ditto shaped shaped hook 
process process 
EE EEE eee 
