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Show 6 5 8 SIR C. ELIOT ON NUDIBRANCHS [J u n e 19, T. anceps Bergh (Bull, of Museum of Comparative Zoology, Harvard, 1890, p. 169) is a doubtful form omitted by Bergh in subsequent lists of the genus, and perhaps akin to Atagema. T. hispida is also regarded by Bergh as doubtful, but, so far as one can judge from the plates (Opisth. der Sammlung Plate, p. 527, pis. xxx. & xxxi.), seems to possess most of the characters of the genus. It is sometimes difficult to distinguish the external characters of Thordisa and Trippa verbally, for some species of Thordisa have soft tubercles which bear secondary papillae or filaments. But whereas the typical Thordisa is rather flat and covered with soft, elongate papillae, the typical Trippa is spongy, though often full of spicules, and bears large, irregularly compound tubercles, with pits between them. T rippa ornata Bergh. (Bergh in Semper's Reisen, Heft xii. p. 543, and Heft xvii. p. 905. Id., Siboga-Expeditie, Opisthobr. p. 129. Cf. Kelaart, Doris intecta, 1. c. I. p. 302.) The original specimen described by Bergh in 1877 was reddish-brown with a yellowish median longitudinal band. In another specimen (1890) he found a white longitudinal band (not, however, marked in the figure, Semper's Reisen, Heft xvii. pi. lxxxiv. fig. 7), and suggested that the animal might be Kelaart's Doris intecta. This suggestion is rendered even more probable by the description and figures in the 1 Siboga ' Expedition volume. Kelaart's figure represents a reddish-brown, tuberculate Dorid with a white line extending from the branchiae to the rliinopliores. The only objection to identifying it with Trippa ornata is that it is said to have long oral tentacles, whereas the accounts of the preserved specimens suggest that the tentacles are rudimentary. As Doris intecta is said to be very common at Trincomalee in low water during September and October, the identity may perhaps be decided by an examination of further specimens. T rippa luteola (Kelaart). (Plate XLII. fig. 4.) (Thordisa caudata Farran, 1. c. p. 341. Doris luteola Kelaart, 1. c. I. p. 299.) Two specimens from the reef at Tamatave, Madagascar, given me by Prof. Voltzkow. A note with the specimens says : " Saum citronen galb. Fuhler schwarz. Kieme schwarz." Through the kindness of Prof. Herdman, I have also been able to examine the single type specimen of Thordisa caudata in the Museum of Liverpool University. All three specimens undoubtedly belong to the same species. The specimens from Madagascar are much bent, but if straightened out would be 35-40 mm. long and 20-25 broad. The colour is a rather dirty white. The back is in most parts covered with flat tubercles of various sizes, generally bearing secondarv |