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Show 100 MR. F. F. LAIDLAW ON POLYCLADS [May 26, the Polyclad fauna of the Indian Ocean, and especially of the African coasts. As a matter of fact, I believe that no shore-haunting species have hitherto been recorded from the East Coast of Africa, save from the Red Sea and from the neighbourhood of the Cape of Good Hope. Of the four new genera described in the present communication, Phylloplana is closely related to Leptoplana, Avhilst the other three are of unusual interest. In order to keep the paper within reasonable limits I have done little more than give an account sufficient, I hope, in each case, to render the future identification of the species a matter of certainty. I have not attempted to enter into any detailed account of the anatomy of the various species, or to deal with many of the interesting questions which have been suggested to me by their structure. I have given a list of species of one or two of the genera, with their distribution and some of their more obvious characters, as I believe such lists may have some use. My thanks are due to Mr. Crossland, who has permitted me to examine and describe this collection, and has furnished me with useful notes and coloured sketches of some of the species. I am also indebted to Mr. A. D. Darbishire for drawings reproduced on Plate IX. Family PLANOCERID^E. PLANOCERA CROSSLANDI, sp. nov. " White, leaf-like form. Dredged off the mainland coast in 10 fathoms." Slightly damaged. Length 22 mm. Breadth 16 „ "Mouth"* from anterior end... 12-5 „ o* aperture from " mouth " ... 4 ,, 2 n i, male T5 „ Tentacles from anterior end ... 6 ,, Only a single specimen collected. This species is most closely allied to PI. armata mihi [5]. The eye-spots have an arrangement very similar to that found in the latter species. There is a dense cluster at the base of each tentacle ; the paired group of brain-eyes lying in front of the brain is more extensive than that behind it. The epidermis unfortunately has entirely disappeared from the surface of the specimen. The muscles of the body-wall are very similar to those found in PI. armata. The brain is well defined and of moderate size. The gut has the character typical of the genus, viz. some seven pans of large branches from the main gut, each of which gives off numerous smaller ramifications which do not form any anastomoses. The gut is without the peculiar diverticula found in PI. armata. * The term " mouth " is used to mean the opening of the pharyngeal pouch to the exterior. |
