248 Records of the Indian Museum. [Wor Welk: 
which swarmed among water-weeds at the edge of the Mahanaddi 
and also in a canal at the same place. J,oose specimens were sub- 
sequently found in bottles of Caridina sumatrensis from Sambalpur 
in Orissa and Rajmehal in Bengal. 
In the river and canal at Cuttack small Decapod and Schizo- 
pod Crustacea are extremely abundant. At least three species of 
Caridina (C. nilotica, Roux) (s.l.), C. propingua, de Man, and 
C  sumatrensis, Bouvier, occur among weeds at the edge, and also 
numerous small (mostly immature) Palaemonidae; while the 
water is often full of large shoals of the little estuarine Mysidae 
Potamomysts assimilis and Macropsis orientalis, Tattersall (10). 
In spite of a careful search, I did not find Caridinicola on any 
species of Palaemon or Mysidae at Cuttack or on Caridina milotica. 
I cannot, however, be sure that it did not occur on C. sumatrensis, 
although all the specimens of Cavidina cn which I know that I 
took it are assigned by Mr. Kemp to C. fropinqua; for the 
immature individuals of the two prawns resemble one another 
very closely. 
I have not been able to find Caridinicola on Caridina propin- 
qua in the neighbourhood of Calcutta, but this may be due to the 
fact that the prawn in this district is only found in distinctly 
brackish water, whereas the water of the Mahanaddi at Cuttack is 
very nearly, if not quite, fresh. That of the Mahanaddi at Sam- 
balpur and of the Ganges at Rajmehal is of course quite fresh. 
Nothing is yet known of the distribution of Cavidina propinqua, 
which has hitherto been recorded only from the Ganges delta, 
but it is very closely related indeed to C. fossarum, Heller, from 
Persia, and it is probable that closely allied forms extend all 
over the territory intermediate between that country and Lower 
Bengal. C. sumatrensis appears to be distributed over a consider- 
able part of the Oriental Region. 
The host of Scutariella is Atydephyra desmarestit, the only 
non-cavernicolous European Atyid. 
The habitual position of Caridinicola on its host is inside the 
gill-chamber, in which it lies attached to the gills. In most cases 
it can be readily detected in this position with the aid of a low- 
power microscope by an external examination of the prawn, whose 
integument is rarely pigmented so deeply as to render the opercu- 
lum opaque. If the water in which the prawn is living, however. 
becomes foul or if any noxious substance is added to it, the worm 
immediately emerges from the anterior end of the chamber and 
makes its way rapidly along the antenna or antennule. After 
gesticulating wildly in a manner that will be described presently, 
it then makes off in search of a new environment, being by no 
means wholly dependent on the prawn for the power of locomotion. 
For this reason very few specimens can be found on prawns which 
have been kept in ‘captivity for more than a few hours, unless 
precautions are taken to keep the water fresh. 
Caridinicola, though not markedly gregarious, is usually 
found in parties of two or three and, so far as my observations go, 
