No. V.—PELAGIC CRUSTACEA DECAPODA OF THE PERCY SLADEN 
EXPEDITION IN H.MS. ‘“SEALARK.” 
By Stanuey Kemp, B.A., Assistant Superintendent, Indian Museum, Calcutta. 
(Plate 7 and 1 Text-figure.) 
(CoMMUNICATED BY PRror. J. Stantey Garpiner, M.A., F.R.S., F.L.S.) 
Read 19th June, 1913. 
THE pelagic Decapod Crustaceans obtained by Mr J. Stanley Gardiner comprise only 
thirteen determinable species represented by adult or sub-adult individuals. Possibly if 
larger nets had been used the number would have been much greater ; for such actively 
swimming animals as Decapods readily avoid capture, and even the net, 4 ft. square, 
employed by Mr Gardiner was not large enough to obtain them in any numbers. 
The collection is, however, a very interesting one, more particularly when comparison 
is made between the species it contains and those found further to the north in the 
Arabian Sea and the Bay of Bengal. Special attention has been paid recently to the 
midwater fauna of these areas by the Royal Indian Marine Survey Ship “ Investigator” 
and a large collection of pelagic Decapoda has been obtained. It is noteworthy that only 
four of the thirteen species found by Mr Gardiner are common to the two collections. As 
specific instances of this difference it may be mentioned that Acanthephyra sanguinea, 
Alcock, the common species of the genus in the Arabian Sea and Bay of Bengal is replaced 
in the present collection by the allied A. purpurea, A. M. Edw., and Lucifer acestra, 
Dana, obtained by Mr Gardiner in great quantities, appears to be of the rarest occurrence 
in Indian seas; the Sergestidee also of the two areas are wholly different. Gennadas 
parvus, Bate, seems to be rare in the more northerly situations, and G. scutatus, Bouvier, 
found in its typical form in the area surveyed by Mr Gardiner, is represented nearer the 
coasts of India by a distinct race for which the name indicus is proposed. 
I have to thank Mr Gardiner not only for entrusting me with this interesting 
collection, but also for the patient manner in which he has waited for the completion 
of my report, long delayed through pressure of other work. 

