ENTOMOSTRACA FROM CEYLON. 129 
in the posterior part of the abdomen, which perhaps are the seat 
of the red pigment. 
The species is one of peculiar interest in more than one respect. 
The female is of a perfectly normal type, but the male differs strik- 
ingly from any species of Streptocephalus hitherto described. In 
particular it is distinguished by the enormous development of the 
frontal processes, which about equal the second antenne in size. 
In the majority of the species of this genus the frontal processes 
are reduced and fused into a small plate, sometimes showing traces 
of its originally paired origin by the presence of a small emargination 
of the tip; for example, S. rubricaudatus, Klunz. and S. vitreus, 
Brauer. In others they are almost entirely suppressed, as in S. 
purcelli, Sars. In only one or two cases are they very conspicuous. 
These are S. proboscideus, Frauenfeld, and S. newmanni, Thiele. The 
frontal processes of the latter are of almost exactly the same type 
and relative size as those of 8. spinifer. They differ in that the main 
fused stem gives off on either side a branch, and is itself produced 
into a long recurved process. It is, in fact, a trifid frontal process. 
The possession by the male of spines on the abdominal segments, | 
which has suggested the name given to the species, is a striking, but 
not distinctive, feature of it. In S. newmanni also the abdomen is 
armed with spines in the male but not in the female, but in this case 
they are ventral and unpaired. It appears to be the rule among the 
Branchipodide that such spines, when present, should be possessed 
by the female and not by the male ; for example, Chirocephalus spini- 
caudatus, Simon, and Chirocephalus carnutanus, Brauer (see Simon, 
1886, p. 400). These two species are exceptions which prove that 
the spines have no accessory sexual function as one might perhaps 
otherwise assume. 
A point of more morphological importance is the possession of a 
marked rostrum. Traces of a rostrum are indeed present in more 
than one species; for example, Chirocephalus grubei (Dybowski) 
and Branchipus pisciformis (Schaeffer). In the latter the rostrum 
is represented by a broad, truncated outgrowth, and I know of no 
species in which a definite pointed rostrum occurs like that of Strep- 
tocephalus spinifer. 
Order : CoPEPODA. 
Diaptomus Greeni, n. sp. (Plate IT.) 
Female ; Cephalothorax stout, the greatest breadth falling about 
the first free segment. The last segment produced on either side 
into a large wing with two notches (fig. 1). Abdomen consisting of 
