OCR Text |
Show 1 0 0 0 . ] OF SOUTHERN INDIA AND CEYLON. 6 7 5 some oi tlio older species nra very imperfectly known. Bergh recognises eight species altogether, and in the commonest, Sc. pelagica, four varieties besides the typical form. Basedow & Hedley (Trans. Roy. Soc. South Australia, vol. xxix. 1905, pp. 148-9, pi. ix. tigs. 1 tfe 2) have recently figured some forms of very divergent appearance which they refer to this species. According to the structure of the radula the species fall into two groups. In Sc. pelagica the teeth are flat and bear only a few denticles: Sc. marmorata belongs to this group. In Sc. elegantula and Sc. bicolor the teeth are erect and bear more numerous (10- 15) denticles. Alder and Hancock (I. c.) described two species: Sc. viridis and Sc. marmorata. No specimen of the former is forthcoming, but the animal should be recognisable by its shape if found again. Notes on the specimens of Sc. marmorata are appended. On Kelaart's drawing of the animal which he has called Scyllcea (?) draccena, Hancock has written :-" Not a Scyllcea ; belongs to the Bullidse." The drawing suggests that it is a mutilated Lobiger with only three wings. But no shell is visible. SCYLLiEA MARMORATA A. & H. (A. & H. 1. c. p. 136.) Two specimens from Newcastle, preserved in alcohol. They are high and narrow, about 15 mm. long and 3 mm. broad. One has been dissected already, and two large globular masses of the hermaphrodite gland are very conspicuous. So far as can be now seen, the external characters are as described by Alder and Hancock. The most remarkable features are the row of very distinct yellow tubercles on each side of the body, and the large size of the whitish branchiae which are set inside the cerata and on the caudal crest. The largest tufts are 3 mm. wide and the branches 2 '5 long. The jaws are greyish, of the shape usual in the genus, with edges which are irregular in places, but not denticulate. The surface is covered with fine striatioiis and with numerous very short rods, which look like minute spicules. In parts near the edge is developed a fine mosaic. On the labial cuticle are two grey triangular patches with a colourless triangle between them. They appear to be of the same substance as the jaws and exhibit the same short ro:ls. This formation is perhaps analogous to the labial armature in Bornella. The radula is, as usual, somewhat fragile and decayed, but consisted of at least 16 rows when complete, with at least 27 teeth in the longest rows. The teeth do not differ materially from those of Scyllcea pelagica. The central tooth has a strong, flat, elongate, rectangular base, but is not very broad. It bears four denticles on either side of the central cusp. The first laterals are similar to it, but narrower. The rest become gradually broader and bear as many as six longish denticles on either side. |