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Show 1892.] ON A N E W MONKEY FROM SUMATRA. 613 fissure) there are numerous connecting furrows ; the whole surface of the brain is indeed divided up by a network of furrows with a development far in excess of anything met with in any other Rodent known to me. The very number and variety in direction and extent of these furrows make it quite easy to select some which can be identified with those upon the cerebral hemispheres of other Rodents. It is of course difficult, if not impossible, to come to any definite opinion as to the significance of the furrows upon this particular brain ; if they are an accidental expression of the possibilities of modification in the brain-surface, it is noteworthy that the Rabbit departs very widely from the Simplicidentati. In the latter group the tendency upon the whole appears to be a stronger development of longitudinal furrows, thus resembling the Ungulata. 2. O n a new Monkey from North-east Sumatra. B y R. C O L L E T T , C.M.Z.S. [Received November 8, 1892.] (Plate XLII.) During the years 1888 and 18S9, Herr Iversen, one of the pre-parators of the University Zoological Museum of Christiania, resided on the north-east side of Sumatra in order to collect specimens for the museum. Through the kindness of two young Norwegians, the Messrs, Kamstrup, who are established there, one in the district of Langkat, the other in that of Deli, Herr Iversen, by living in turns on their estates, has been enabled to make a very important collection of the vertebrated animals of those districts. As the collection of Vertebrates is not yet completed, but is being steadily increased by Messrs. Kamstrup themselves, I intend, at a later opportunity, to give a general account of the whole of the materials furnished from these pari s. On the present occasion, however, I wish to give a short diagnosis of a Semnopithecus which does not appear to have been previously described, and to which I have great pleasure in attaching my friend Mr. Oldfield Thomas's name. SEMNOPITHECUS THOMASI, sp. n. (Plate XLII.) Diagnosis.-A central occipital crest sloping at first backwards, but reversed on the occiput; a lower (indistinct) crest on each side of the forehead. Colour above dark grey, white underneath ; hands and feet black. The cheeks, front, and forehead are white ; a black stripe from the upper jaw to the ear, and a black central stripe on the forehead ; the very old male darker, with the upper part of the head brownish black, front whitish. Locality.-Langkat, N.E. Sumatra (7 specimens procured ; University Museum, Christiania). In form and general appearance this Monkey resembles the group |
