The result of the author's examination of diseased birds has been to confirm the statements of Drs Cobbold and Crisp, lately published in the “British Medical Journal,” that diseased grouse, or at least the emaciated birds commonly known as “piners,” owe their depraved condition to a small thread-like worm (Strongylus pergracilis, Cobbold) which infests the cæca. The author concurs in the opinion entertained by most of those who have written on the subject, that the tape-worm (Tœnia calva), which is well known to infest the grouse, is not the cause of the disease. The Tœnia is undoubtedly often present along with the Strongylus in diseased birds, but is often found by itself in plump healthy grouse. The worst cases seem to be those in which both are present in quantity, as in one examined by the author, whose cæca was crowded with Strongyli, whilst the intestine contained ten tape-worms, the whole weight of the bird, a full-grown cock, being only 15½ ounces.