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 Jan., 1917 FURTHER NOTES ON THE WHITE-THROATED SWIFT new throughout and were being used for the first time. No. 3 was larger in all dimensions than any of the other nests and there seemed to be at least two layers under the nest in use, and in the layer directly under the new nest the remains of eggs could be seen. It is my opinion that the nest had been used in at least two former seasons. The two lower layers were not substantial, prob- ably having decomposed due to age and insects. Photos of set no. 2 and set no. 3, with nests, show difference in size and at the same time the general appear- ance of typical nests. Nests are constructed, for the most part, of chicken feathers and grasses cemented together and to the rocks, probably by saliva. They vary in size to suit the space between the walls of rock and are usually shallow and narrow. The following dimensions, in millimeters, show the range of variation. Fig. 2. WHITE-THROATED 0W1FT, SET NO. 3. NOTE LARGE SIZE OF THIS NEST AS COMPARED WITH NO. 2 AND THE SPOTTED CONDITION OF TtIE EGGS. Nestfor Outside Inside Set No. Depth Length x Breadth Depth Length x Breadth I 51 89x63 25 63x57 2 63 140x48 38 70x41 3 57 146x76 38 102x57 4* 70 107x52 ................ 5 51 102x51 19 70x44 Both the vertical and the horizontal cracks are used as nesting sites, but with the exception of set no. 5 all that I took were from vertical cracks. It is almost impossible to take nests from horizontal fissures without destruction of the eggs and in the exception noted, a rock weighing at least 35 tons was re- moved. This can be seen in the photo. The location of set no. 6 was rather un- usual, being reached by going into a vertical crack about three feet, then up eighteen inche. s, then to the side about eight inches.
 * Measurements by Y/. S. Swartb, Museum of Vertebrate Zoology.