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Show 596 MESSRS. SCLATER AND SALVIN ON PERUVIAN BIRDS. [Nov. 25, sions of the bodies of the two ; but the Cephalophus dorsalis, nevertheless, has much the stronger build. The head and ear of the latter are relatively and absolutely the largest, whilst the length of the tail preponderates in C. maxwellii. „ , ,. -, .... r r C. dorsalis. C. maxwellii. in. in. " Length from snout to root of tail (taken laterally) 27| 26 Height at shoulder (with straightened limb) .. 16 16 at hip (with straightened limb) 17 17 Depth at chest 7 7 Length of tail to tips of hairs 4 5| of tail to the end of the vertebrae 3 4| Head : length, muzzle to occiput 7 6| Ear, in greatest length 3 2| " In the Bay Antelope the nasal and zygomaxillary regions are half an inch broader than in the other species, and they are likewise more prominent and arched both across and lengthwise. " The inside of the ear of C. maxwellii is covered with long hairs ; in C. dorsalis the ears are bare, or have but a trace of short hairs near the margin. " Both species possess interdigital pits on all the feet, and both have shallow, rudimental suborbital glands; but the Bay Antelope differs markedly from the other in its possessing two deep inguinal sacs: there is neither an external nor internal trace of these in C. maxwellii. " As regards the internal organs, these are formed on the same ruminant model, there being four cavities in the stomach and a capacious caecum. There is a trenchant difference, however, in the comparative lengths of the intestinal tract, the stronger animal having the shorter eut. Thus in _ , ,. _ ° ° C. dorsalis. C. maxwellii. ft. in. ft. in. " The small intestine measures 22 0 25 3 The great intestine, minus caecum 7 7 10 3 The ceecum 0 5| 0 8 .< From the animals being both adult, of the same sex, and, broadly speaking, similar in size, it may reasonably be inferred that this striking variation arises from specific difference. Our want of knowledge of the precise food and habits of each in their native haunts debars a physiological reason being guessed at." 10. O n Peruvian Birds collected by M r . Whitely. By P. L. S C L A T E R , M.A., Ph.D., F.R.S., and O S B E R T SALVIN, M.A., F.L.S.-Part V * Since our last communication to the Society upon this subject two small collections have been received from Mr. Whitely. The * For Part IV. see P. Z. S. 18G9, p. 151. |