| OCR Text |
Show 290 SIR C. ELIOT ON NUDIBRANCHS [Nov. 29, H e rm ^ i d a S t il ig e r v a r ia n s , sp. n. (Plate XVI. fig. 6.) Several specimens from Prison Island in Zanzibar Harbour, found in green-branched seaweed, in which they are practically invisible. The colour was very variable, ranging from dark brown to white, but was as a rule brilliant green. After being kept in captivity for a night, the animals grew perceptibly paler. The main colour was largely hidden, except at the sides of the body and in the centre of the back, by numerous lines of a deeper colour, generally dark bright green, and in some, but not all, specimens there were more or less extensive patches of crimson lake. The form was somewhat elongate, and the maximum dimensions 10 mm. by 2 mm. The foot was fairly broad and green. The preserved specimens are colourless and semitransparent. They have contracted into an oval or nearly semicircular form, and strongly resemble small tufts of seaweed. The centre of the back is bare, and through its transparent integuments can be seen a great number of circular folliculate organs which are apparently the follicles of the hermaphrodite gland. There are about ten transverse rows of cerata in the largest specimens, containing four (or sometimes five) cerata on each side of the central space. The two innermost cerata of each row are large (about 3'50 mm. x 2 mm.) and somewhat inflated. The others are very much smaller and look like mere tubercles. They all contain ramifications of the liver, consisting of one large main stem from which spring three or four quite small and short branches. The bladder-like pericardial prominence is somewhat elongate; in front of it and fused with it is the anal tube. The rhinophores are entire and not grooved. In the largest specimen they are about 3 mm. long and rather thick, as if conti'acted. Below them are two lumps which may be regarded either as a frontal veil notched in the middle, or as rudimentary tentacles. The anterior angles of the foot are not much produced. The tail is pointed but not long. The radula was examined in several specimens, and was found in all to consist of four or five teeth in the ascending part and six in the descending, while the number in the heap did not seem to exceed six or eight. The teeth (PI. XYI. fig. 6) are somewhat like those of Ercolania siottii (v. Trinchese, ‘ Aeolididae del Porto di Genova,' vol. ii. pi. x. figs. 7 & 8), and have a broad spoon-like hollow into which the tooth behind fits. In my account of Mr. Gardiner's Nudibranclis (‘ Fauna and Geography of the Maldive and Laccadive Archipelagoes,' vol. ii. pt. i. p. 571, and pi. xxxii. figs. 9_& 10) this animal is erroneously figured as Hermcea minor. It is, however, not a Hermcea and not identical with Mr. Gardiner's specimen. That specimen is a Hermcea, and may possibly be H. minor, as there suggested. |
