Ol'ISTHOBRANCHIATE MOLLUSCA. 335 



length only I'l centims.. the other is somewhat larger, length 3 5 centims., but both 

 fall far short of the size usually attained by members of the genus, and are probably 

 immature. 



Professor Herdman's notes, referring to t lie larger specimen, are " scarlet and 

 white, swimming species," and "red blotched with white, especially at sides of 

 mantle." The spirit specimen is somewhat depressed, of a dirty semi-translucent 

 white colour. The mantle wide and thin and frilled at the margins, total width 

 2"4 centims., free margin - 55 centim. The free edge of the mantle in front of the 

 head is 2 - 5 millims. wide and has a smooth entire margin. 



Rhinophores far apart, of the usual shape, with about 28 lamella?. Tentacles 

 large ; flattened, with crenated margins. Branchias in 6 groups surrounding the short 

 tubular anus. 



The jaws are powerful, with about 8 transverse ridges. 



The radula has about 32 rows of teeth, the formula being 46-0-46. The innermost 

 2-3 teeth on each side are imperfect. 



The identification of species of Hexabranchus from preserved specimens is, as both 

 Bergh and Eliot (12) have remarked, a matter of difficulty, but in this instance 

 there seems little doubt that the specimen is Hexabranchus marginatus, as the white 

 marginal blotches, crenate margin to tentacles, and distinct anal tube, as well as the 

 agreement of the radula, seem to indicate. 



Collingwood's Albania formosa (8, p. 132), from Formosa, seems to be undoubtedly 

 the same species, as also, perhaps, Alder and Hancock's " Undescribed species of a 

 new genus apparently related to Goniodoris," from Madras (5, Plate XXXIII., 

 fig. 20). 



Sub-family : DISCODORIDID^E. 

 Discodoris labifera (Abr.). Plate I., figs. 17 and 18. 



There are three small specimens of Discodoris, one from the pearl banks oil Aripu 

 and two from Oheval Paar, which I doubtfully refer to the above species. The 

 animal is quite unrecognisable from Abraham's original description (7) ; but on 

 examination of what appeared to be the type specimen in the British Museum, I found 

 that, making allowance for difference of size, it agreed fairly well in external features 

 with the Ceylon specimens. The British Museum specimen is undoubtedly a Disco- 

 doris, as the partially protruded buccal armature is distinctly visible, though there is 

 no mention of this in Abraham's description. There are also in the British Museum 

 collection some unnamed specimens from South Africa which apparently belong to the 

 same species. 



The Ceylon specimens measure about 1*6 centims. in length, and the width of 

 the most symmetrical is 0'95 centim. The colour of the Aripu and one of the Cheval 

 Paar specimens is a dirty greyish-brown. The other Cheval Paar specimen, though 

 much distorted, has preserved its colour and texture better than the rest. It is of a 



