18 The Malacostraca of Natal 
DoTILLA CLEPSYDRA, sp. nov. Plate V. 
The name clepsydra is chosen to denote the agreement between this 
species and Aleock’s D. clepsydradactylus in regard to the chelipeds, 
of which he writes, ‘The fingers are much longer than the palm; in 
the adult male they are extremely slender, and each has a large tooth 
arranged so that when the tips of the fingers are closely opposed these 
two teeth meet and leave an hour-glass-shaped space between the 
closed fingers” (loc. cit., p. 367). The second sentence is emphasized 
by italics and agrees with fig. 2 on pl. 63, Illustr. Zool. Investigator, 
published in 1902. On further testing the agreement, however, I 
found that it did not extend to the fourth joint of the chelipeds, since 
Alcock states that in his species they ‘have no spine on the arm.” 
By spine is evidently intended the proximal tooth or process which 
Dr. de Man finds in the adult male of the typical species D. sulcatus 
(Forskal), though wanting in the female (Zool. Engebn. in Nederland. 
Ost. Indien, vol. ii, p. 311, 1892). On a character variable between 
the two sexes of the same species reliance could scarcely be placed for 
distinction between species and species, if it stood alone. This is not 
the case here. In the Durban specimen the surface of the carapace 
agrees more nearly with Alcock’s D. affinis, especially in respect of 
the large distal area, a triangle with convex sides and the base 
rectilinear ; and, besides differences in the tympana, the fingers of the 
ambulatory limbs show a marked divergence, being here all nearly of 
the same size, while in Alcock’s species those of the fifth perzeopods 
are much longer than those of preceding pairs. 
As is well known, the third maxillipeds in this genus have a boat- 
like bulge, formed by the large third joint and larger fourth, the 
latter almost concealing the last three setose joints, and helping to 
conceal the slender exopod which is devoid of a flagellum. The close 
packing of other mouth-organs within the boat adds something to the 
difficulty of their disentanglement. 
In the mandibles the very large single-jointed palp by its curvature 
and notching implies a small basal joint coalesced; it carries long 
feathered sete on its outer margin proximally, followed by rows of 
unequally short sete of minutely battledoor shape. Similar setz of 
various sizes occur also on the large middle lamina of the second 
maxilla, and fringing the terminal joints of the second maxillipeds. 
The part which seems to represent the three terminal joints in question 
is broader than either of the two preceding joints and a little longer 
than both combined ; this compact mass has an oblique line perhaps 
marking the area of the finger, 
