COTILE DILUTA, sp. n.
Cotile riparia, pt. auct. ex Asia centrali.
C. similis C. riparioe, sed ubique dilutior et torque praepectorali vix obvio.
Hab. in Asia centrali.
Adult male. Similar to C. riparia, but very much paler brown above, and the throat-baud also very light brown and overshaded with ashy, so that the collar is not distinct. Total length 4.8 inches, culmen 0.4, wing 3.85, tail 1.8, tarsus 0.4.
Adult female. Similar to the male. Total length 4.6 inches, culmen 0.4, wing 4.05, tail 1.95, tarsus 0.4.
Hab. The neighbourhood of Tashkend in Central Asia.
THE late Dr. Taczanowski, in his ‘Faune Ornithologique de la Siberie Orientale,’ states that Mr. Janskowski, the well-known explorer of Russian Mantchuria, procured five examples of a Sand-Martin on the Sidemi River, close to the frontier between Ussuri Land arid China, and not far from Vladiowstock : they were obtained by him towards the end of May. In the description of the species, which he refers to C. sinensis, Dr. Taczanowski distinctly speaks of a pectoral band, which, he says, is less pronounced in the Ussuri bird than in C. riparia. As is seen in our 'Key ’ to the species of Cotile, C. riparia and C. sinensis belong to two different sections of the genus, and as we entertained great doubt as to Dr. Taczanowskii identification, we wrote to our friend Mr. Stolzmann, who very kindly sent over the specimens in question. We find them to be absolutely typical C. riparia, not even C. diluta (as we expected), and they certainly have nothing to do with C. chinensis.
Of the pale race of C. riparia, which we propose to call C. diluta, we have seen two specimens collected by the late Dr. Severtzoff and sent to the Natural History Museum by Dr. Pleske. These birds were collected by Dr. Severtzoff on the Badam River, near the fortress of Tchemkent. They have much the appearance of C. sinensis, as the throat-band is very indistinct and is shaded with silvery grey ; but the band is absolutely represented, and in order to avoid all doubt as to the relations of the species, we may add that the development of the tarsal tuft proves that it is a form of C. riparia and does not belong to the C. sinensis group.
Of the winter range of this species we have little or no knowledge. The few specimens in the British [Museum which seem to belong to the Pale Sand-Martin are in bad condition ; but we think that two birds collected by Griffith near Pushut in Afghanistan are referable to C. diluta, and a skin from Madras (Jerdon) may also belong to it, as well as a specimen collected by Mr. Pratt near Ichang in Central China. Now that attention has been drawn to this pale form of Common Sand-Martin, we shall doubtless receive more information respecting it, as a larger series than we possess in England is necessary for the correct determination of its range.
For the geographical distribution of this species, vide infra, Plate 30 [Map].
COTILE DILUTA, sp. n.