G. H. H. mentions in NATURE of Sept. 22 his having found on a swallow in the month of August two slate-coloured insects. On the 15th of July last, when hauling a seine net in Studland Bay, near Poole, with some fellow members of the Linnean Society Club, I picked up at the foot of the low cliff a young saud-martin, which had seven of these parasites (Ixodes plumbea) affixed to the skin of the head, giving it the appearance of having a slate-coloured fleshy crest. The poor little bird exhibited the symptoms described by your correspondent. I found it panting and apparently exhausted on the ground, and it remained stationary without making any effort to escape. The fishermen of our crew informed me that they often pick up martins with these ticks adhering to them.