NOTES ON NTJDIBRANCHS. 
89 
say that the upper lamina of the anterior pedal margin is not notched, 
whereas here it is divided in the middle. But, as explained above, 
this notch, though distinct when seen, may be hidden and easily 
escape notice. 
Also, after comparison with Bergh’s original specimens in the 
British Museum and Copenhagen Museum, I think that Disc, fragilis 
is the same animal as his Disc . morphcea. His specimens have lost 
their colour, but what remains of it and the texture support the 
identification. The only difference to be noted is that the original 
specimen from the Philippine Islands had thickenings on the rhachis 
resembling teeth. But these were not found in the Challenger 
specimens, and they are probably often absent, perhaps only 
occasionally present. Against this difference may be set not only 
the general resemblance of Disc, fragilis to Disc, morphcea, but the 
following coincidences in details -(1) The central nervous system 
is granulated and the divisions are not distinct; (2) the two blood 
glands are separate and divided by the central nervous system ; 
(3) the stomach is laminated internally ; (4) the intestine dips 
down under the right side of the liver and comes up again; (5) 
the praeputium is laminated; and (6) the oral tentacles have a 
spiculous core. 
Discodoris concinna (A. & H.). 
= D. concinniformis , B. 
See A. &H. I., p. 118 ; Eliot I.,pp. 251-2 ; and Eliot II., p. 1005. 
One specimen from Trincomalee, which is probably immature, 
being only 26 mm. long and 16 broad. According to the notes it 
was brownish gray when alive, with darker patches. Down the 
centre of the back ran a line of not very clear whitish areas; on 
either side of this was a line of dark patches more deeply coloured 
than the rest. There were numerous other patches, smaller and 
fainter. 
The grayish tint of the animal (which is well reproduced in 
Alder and Hancock’s plate) is due to the papillae with which the 
back is densely covered being gray, irrespective of the ground colour 
on which they stand. The branchial pocket is raised, but not 
stellate. 
The buccal parts are as usual in the species. The formula of the 
radula is about 27 X 60 '0 *60, The teeth at the end of the rows 
are long and thin, but not denticulate or degraded. 
This species is common in the Indo-Pacific, and extends north¬ 
wards to Japan. It attains a length of 6-7 centimetres, and the 
general colour is sometimes bluish rather than brown, as in this 
specimen. But the curious gray effect produced by whitish papilke 
on a darker ground is always noticeable. It appears to be nearly 
related to D. notha from the West Indies. 
