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Show 132 MR. O. SALVIN ON THE BIRDS OF VERAGUA. [Jan. 24, Nicaragua now stands, was open, the species of the northern portion of South America and Costa Rica were identical, and but few neotropical forms existed northward of the separation. A further subsidence must then have isolated Costa Rica, where during a lengthened period most of the species have become slightly modified. A rise of land to the extent of the present contour of Central America then took place. The old straits, now land, have been occupied by contending allied races, sometimes the Costa Rican, and sometimes the southern race prevailing, occasionally the southern race penetrating through the country of its representative and driving it before it. Towards the south the Costa Rican species have soon met with their representative races, by which their range has been stayed; while northward, impeded by no such barrier, they have spread as far as climate and the supply of their necessary food would allow them, the most strongly defined limit in this direction being, probably, the northern boundary of the tropical virgin forest. TuRDIDiE. 1. C A T H A R U S GRISEICEPS, Salvin, P. Z. S. 1866, p. 6S. Santa Fe', Veragua. 2. CATHARUS FUSCATER (Lafr.). My iotur dus fuscater, Lafr. Rev. Zool. 1845, p. 341. Catharus fuscater, Sclater, Cat. A. B. p. 2 ; Salvin, P. Z. S. 1866, p. 69. Cordillera of Tole. Arce' has sent a single male specimen of a Catharus which agrees closely with Mr. Sclater's examples from Ecuador. The bill, however, is somewhat larger and, in this fresh specimen, of a brighter orange-colour. C. fuscater is no doubt the southern representative of C. mexicanus (Bp.) (Scl. Cat. p. 1), which occupies its place from Costa Rica to Mexico. Both species are inhabitants of the " tierra caliente," and appear to be decidedly scarce in the countries in which they are found. 3. TURDUS GRAYI, Bp.; Lawr. Ann. N. Y. Lye. viii. p. 174. Santa Fe, Veragua ; David (Hicks). Ranges as far southward as Panama. At Santa Martha T. luridus, Bp. Notes Orn. p. 28, replaces it, a species of which I have recently acquired a specimen, collected by the late Mr. Bouchard. This differs from a Panama specimen of T. grayi in having the under surface much paler, the crissum being nearly white. The upper surface, too, is more olivaceous and hardly shows a cinnamon tinge, the tail is squarer, and the dimensions, especially the feet, smaller. Total length 9, wing 4'5, tail 3*9 inches. 4. TURDUS LEUCAUCHEN, Sclater, P. Z. S. 1858, p. 447; Baird, Rev. Am. B. p. 24. Santa Fe and Cordillera de Tole. Veraguan specimens exhibit none of the marked characters which |