98 MR. 0. THOMAS ON RODENTS FROM PERU. (Jan. 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 New Zealand ; and the columella itself is only a modi- 
fied 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 Mam- 
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 
OupriELp Tuomas, F.Z.S., British Museum. 
[Received 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 my hands for determination by Prof. Taczanowski, of the Warsaw 
Museum, by whom 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. Stolz- 
mann, 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- 
