Dr. J. E. Gray on the Names of the Genus Mystomys. 425 27. Primitia muta, nov. Cytheropsis concinnal, ibid. p. 254, pi. 9. fig. 3. Oblong-ovate, nearly Leperdiiia-shaped ; back straight, ends rounded but unequal; ventral edge convex; surface smooth. Though resembling P. concinna at first sight, it is less cylin-drical, broader at the obliquely rounded end, and its ventral dge is more symmetrically curved : it is near to P. rugulifera in shape. From the Upper Silurian Limestone of Beech ey Island, with P. rugulifera, P. sigillata, Beyrichia clathrata, B. plagosa, and Leperditia gibbera. EXPLANATION OF PLATE XIIL [The figures are magnified about 20 diameters.] Fig.\. Primitia cristata, J. & H. : a, carapace, view of right valve; b, posterior view ; c, dorsal view. Fig. 2. P. umbilicata, J. & H. : a, left side of carapace; b, dorsal view ; c, ventral view ; d, insi-le of valve (filled with matrix). Fig. 3. P. tersa, J. & H. : a, carapace, side view; b, dorsal view; c, ven-tral view. Fig. 4. P. trigonalis, J. & H. : a, carapace, view of left valve ; b, dorsal view. Fig. 5. P. renulina, J. & H. : a, carapace, side view; b, dorsal view. Fig. 6. P. variolata, J. & H. : a, left valve; 6, its edge-view; c, right valve of var. paucipunctata ; d, its edge view. Fig. 7-P. matutina, J. & H. : a, right valve ; b, its edge view. Fig. 8. P. Roemeriana, J. & 11. : a, carapace, side view (left valve); b, pro-file. Fig. 9. P. Beyriehiana, J. & H., right valve. Fig. 10. P. semicircularis, J. & H. ; a, left valve; b, its end view ; c, ven-tral edge. Fig. 11. P. pusilla, J. & H. : a, right valve ; b, its edge view. Fig. 12. P. obsoleta, J. & H. : a, right valve ; b, its end view ; c, edge view (ventral). Fig. 13. P, ovata, J. & II. : a, right valve; b, its end view; c, edge view (ventral). Fig. 14. P. oblonga, J. & H. : a, right (?) valve; b, its end view; c, edge view (ventral). XLVIII. — On the Names of the Genus Mystomys. (In a Letter to Professor Allraan.) By Dr. J. E. Gray, F.R.S., V.P.Z.S., F.L.S. &c. British Museum, Nov. 15, 1865. Dear Professor Allman, As I have been informed that, in your paper on the animal that Du Chaillu noticed as Cxjnogale velox^ you persist in retain-ing the generic name of Putamogale, I venture to send you the following observations, in the hope that I may induce you to re-consider the question, and avoid adding another to the several useless names which the animal has already received.
BioStor
