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Show 98 MR. O. THOMAS ON RODENTS FROM PERU. [Jail. 17, differ but little from those of a bird. Notwithstanding the massive-ness of the skull, nearly every suture is persistent; in the light skull of the Bird nearly every suture is obliterated. " The pier of the mandible explains, and is explained by, that of the Lizard on one side, and the Salamandrian below. The jaw itself is at an early period quite continuous with the hyoid arch ; and that arch is for a time continuous with the auditory columella, as in the Hatteria of N e w Zealand ; and the columella itself is only a modified part of that arch. In its early segmented state, however, and in its later broken-up condition, it comes very near to what is found in the mammal, and greatly helps the morphologist in working out a harmony between this arch in the Sauropsida and the M a m malia. " In the discussion which took place a dozen years ago between Professors Peters and Huxley (for the views of the latter see P. Z. S. 1869, pp. 391-407), as to the early continuity of the mandibular and hyoid arches and their nature, both combatants were right and both were wrong. The two arches are continuous for a time; but that condition does not sustain Prof. Peters's reasoning. The deductions of Prof. Huxley, in spite of the fact that he worked with imperfect materials, will remain true for all time." Prof. Parker's memoir will be published entire in the Society's Transactions.' The following papers were read :- 1. On a Collection of Rodents from North Peru. By O L D F I E L D T H O M A S , F.Z.S., British M u s e u m. [Eeceived December 15, 1881.] (Plate IV.) The collection now described was obtained by M. Stolzmann, the well-known Polish collector, in Northern Peru, and has been placed in m y hands for determination by Prof. Taczanowski, of the Warsaw Museum, by w h o m a nearly complete set has been presented to the British Museum. Every specimen has its exact locality, date, and altitude recorded; and the habits of many of the species have been noted by M . Stolzmann, whose remarks, placed between quotation-marks, are appended to their respective species. The localities from which the collection was obtained are as follows:- Tumbez.-Capital of the province of the same name. Situated on the river Tumbez, at about 4 miles from its outlet in the Bay of Guayaquil (3° S. lat.). Tambillo.-A colony on the river Malleta, a tributary of the Upper Amazons. This river forms the boundary between the pro- |