On new African Mammals. 191 tion of the stalk, and on purely a priori grounds it would be unlikely for a cell to grow out unprotected on a long stalk, and then to form a protective lorica. On the other hand, it is difficult to see how, the lorica being once formed, the stalk could be elongated by a cell situate within the lorica. How-ever, the mode of secretion by similar stalked forms is little understood, but this explanation suggested itself to me after continued comparisons of the younger and older members of a P. dumosa colony (PI. VI. fig. 2, c and d). References to Literature. (i) James Clark. "On Spongise Ciriatte." Mem. of Boston Soc. Nat. Hist. vol. i. pt. 3. 1867. (2) Saville Kent. Manual of the Infusoria. 1881-82. (3) Butschli. "Protozoa Flagellata " in Bronn's ' Thierreich,' Bd. i. Abth. 2. 1883-87. (4) R. France. Der Organismus der Craspedomonaden. 1897. (5) Care Burckj. " Studien uber einige Choanoflagellaten." Arch. f. Protistenkunde, Bd. xvi. Heft 2. 1909. EXPLANATION OF PLATES VI. & VII. Fig. 1 a. Salpingceca vaginicola. Flemming — Fe hematoxylin. Indi-vidual with long lorica. Fig. 1 b. Ditto. Osmic 4 per cent. — carmalum. Fig. 2. Polyceca dumosa, sp. n. Colony, showing method of growth. a, degenerating individual in its lorica ; b, empty lorica ; c, young individual with short stalk and narrow lorica ; d, older individual with longer stalk and wide lorica. Fig. 3. Single individual of P. dumosa, drawn living. Arrows show direction of current of food-vacuoles. Fig. 4. Colony of P. dumosa, drawn living. Fig. 5. Part of colony of P. dumosa. Flemming — carmalum. Fig. 6. P. dumosa. Osmic 4 per cent. — iodine. XXVIII. — Further new African Mammals. By Oldfield Thomas. (Published by permission of the Trustees of the British Museum.) Cercopithecus preussi insidaris, subsp. n. Similar in essential characters to the true Kamerun C. preussi, Matsch., but tending to be darker throughout. Back much less rich chestnut, the hairs of this part with their bases blackish slaty for more than half their length, then with dull buffy subterminal rings and broad black tips. In true preussi they are light slaty for their basal half (or less), their terminal half tawny tipped with black. Tail with
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