IgI6. | S. Kemp: Notes on Crustacea Decapoda. 395 
The abdominal somites are not carinate dorsally. ‘The third 
is very strongly humped and the sixth, which is but little longer 
than the fifth, is produced to a rounded prominence in the middle 
of its posterior margin. The endopod of the last four pairs of 
pleopods bears an appendix interna and is enormously expanded 
in the female (text-fig. 2k); in the male it is not broader than the 
exopod. The margins of both rami bear long setae. 
The telson (text-fig. 2/) is nearly twice the length of the sixth 
somite and is feebly sulcate above. It bears two or three pairs of 
small dorso-lateral spines and terminates in a broad, almost trun- 
cate apex (text-fig. 2m) armed with three pairs of spines, the 
innermost the longest, about equal to the breadth of the apex, 
and the outermost much the shortest. Between the innermost 
pair of spines are two minute spinules, while a similar spinule 
occurs on either side between the bases of these spines and those 
of the intermediate pair. The outer uropods do not reach the 
apex of the telson; they are shorter than those of the inner pairs 
and are rather more than two and a half times as long as wide. 
The long setae that have been described above as plumose 
differ considerably from those to which this term is generally ap- 
plied, for the plumes have not the form of very fine microscopic 
hairs, but are comparatively short and blunt processes from the 
main axis of the seta. 
The largest specimen obtained, an egg-bearing female, is barely 
g mm. in total length; other ovigerous individuals do not exceed 
7 min. 
This curious little species was found at Port Blair near Ross 
I., living among weeds in water from 2 to 4 fathoms in depth. 
We found it impossible to obtain specimens at all freely by the 
usual methods, but if the contents of the net were immediately 
transferred to a bucket of sea-water, individuals were sometimes 
found swimming at the surface and alighting on floating fragments 
of weed. 
The illustration on Plate xxxvi, which is based on sketches 
made from living specimens, will give an idea of the peculiar atti- 
tude that the species adopts. The abdomen is strongly flexed near 
its junction with the cephalothorax, so much so that the third 
segment as a rule almost touches the carapace, and the antennules 
are bent upwards and backwards. In this attitude, and with the 
help of the long plumose setae that the species possesses,! Phyco- 
caris bears the most extraordinarily close resemblance to small 
tufts of algae that are plentiful on the weeds: it was only after 
considerable experience that we were able to distinguish the one 
from the other. The resemblance, which is undoubtedly protec- 
tive, is further enhanced by the colour. The tufts of algae vary 
in shade and are sometimes dull olive-yellow and sometimes 
almost black. Two colour varieties of the prawn, corresponding 

1 These setae are very easily broken off in preserved specimens and are in life 
more numerous and longer than is shown in the figure. 
