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Show 354 SIR C. ELIOT ON XUDIRRANCnS [Dec. 1, The mode of origin of new organs is a morphological problem to which little attention has been given, although it is of great biological interest. The most obvious analogies with the present case are such changes of function and structure as the transformation of the lower part of the pharynx into the thyroid gland or the metamorphosis of part of a gill-slit into the middle chamber of the ear; but I do not remember any case exactly similar to the present where the protoblastic structure, having fulfilled its function, degenerates, but is replaced by a deutero-blastic structure with a new function. It is interesting to notice that the raw materials for this deuteroblastic growth occur in many birds, inasmuch as the relic of the yolk-sac, or protoblast, lingers throughout life, but it is only in a few cases that the relic sprouts again and becomes the new organ. 5. On some Nudibranchs from East Africa and Zanzibar. Part I I I * By Sir C. E L I O T , K.C.M.G., H.M. Commissioner for the East Africa Protectorate, F.Z.S.- Dorididse Cryptobranchiata3, I. [Received October 16, 1903.] (Plates XXXII.-XXXIV.t) This paper contains the results of an examination of a number of Cryptobranchiate Dorids from Zanzibar and the East Coast of Africa referable to Bergh's subfamilies Archidorididae, Disco-dorididae, Diaululidae, Kentrodorididae, and Platydorididse. They include the following species : - Archidoris Bergh. 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. ,, africana, sp. n. ,, minor, sp. n. Staurodoris Bergh. ,, depressa, sp. n. ,, calva, sp. n. Discodoris Bergh. ,, boholiensis Bergh. ,, cceridescens Bergh, variegata. subsp. n. Peltodoris Bergh. ,, angulata, sp. n. ,, aurea, sp. n. Thordisa Bergh. ,, villosa (A. & II.). ,, stellata, sp. n. ,, crosslandi, sp. n. * For Part II. see P. Z. S. 1903, vol. i. p. 250. f For explanation of the Plates, see p. 385. |