IQIO. | C. Exiot: Indian Nudibranchs. 249 
culum of the stomach. The cerata are cylindrical and moderately 
tapering. In the preserved specimens the swelling below the tip 
is less marked than in the figure (fig. 2). 
The jaws are yellowish and bear a single row of distinct 
denticles, which have blunt, but not square, tips. In the specimen 
dissected the radula consists of a single row of 40 teeth, white, 
transparent, and in some respects resembling the type found in the 
genus Aeolidiella. ‘There is a single, low, central cusp, and on 
either side of it 10—15 (rarely more) long, pointed denticles. 
The basal part of the tooth (fig. 3) is large and squarish, not thin 
and crescent-shaped as in Aeoltdvella. 
The verge is conical, and appears to terminate in a small 
curved process which may be a chitinous tube. 
The animals spawned in captivity. The egg ribbon is white, 
and consists of a single simple coil. 
A first view of the radula of this animal suggests that it 
should be referred to Aeolidiella, but when the teeth are separated 
and the broad bases become visible, the resemblance to this genus is 
less striking. Alsoin Acolidiella the jaws are not denticulate. It is 
better, on the whole, to refer the present specimens to the group of 
animals described under the names of Cratena, Hervia, Amphorina, 
Cuthona. Its dentition is not unlike that of Cratena bylgia, but 
the number of teeth and of denticles on the teeth is larger. I 
have discussed the nomenclature of these forms (which have been 
unnecessarily subdivided into many genera) in the Journal of the 
Marine Biological Association, vii, 1906, pp. 363—366, and think 
that the present specimens should be called Cuthona. It is doubt- 
ful, in my opinion, if this genus is really separable from Amphorina, 
but that genus has usually a tapering radula, a peculiarity not 
found in the radula here examined. 
In any case this species shows how the dentition of Aeolidtella 
may have developed out of that of Cuthona. 
[The specimens for which this species has been founded were 
obtained in the Matlah River, a brackish tidal creek, at a distance of 
about sixty miles from the open sea. ‘This is, I believe, the nearest 
approach to a freshwater locality from which Nudibranchs have yet 
been recorded. A sample of water taken from the Matlah at Port 
Canning for analysis not more than a fortnight later three years 
ago was found to contain 25°46 parts of soluble salts per thousand 
(see Rec., Ind. Mus., vol.i, p. 36). The molluscs were found among 
some stones that have been deposited a few hundred yards below 
the town of Port Canning in shallow water near the left bank of 
the river. These stones are partially uncovered at low tide. The 
banks of the river are entirely composed of the dense mud that 
forms so persistent a feature of the Gangetic delta. The food of 
these Nudibranchs probably consisted of a Hydroid (? Bimeria 
vestita), with which they were associated on the stones.—F. H. 
GRAVELY. | 
