We believe that--in this country, at any rate--the word 'quittor' is usually held to indicate one or other of the two latter conditions, and probably the last of these; and that the two first are held of small account, or hardly of sufficient gravity to allow of the word 'quittor' being applied to them. In fact, by defining quittor as a 'fistula,' or little pipe, we have ourselves already indirectly restricted the use of the word to the two latter conditions, for in those varieties known as Simple or Cutaneous and Tendinous, the wound is generally broad and open, or, at any rate, superficial, and can scarcely be strictly described as 'fistulous.' In the two latter, however, a true fistula exists. These, however, have only one essential difference, and that consists simply in the position of the lesion and the structures it has attacked. In the main the symptoms will be the same, the disease in each case about equally serious, and in each the same essentials of treatment will have to be regarded. In our opinion, therefore, a lengthy classification serves no useful end, and we think matters will be simplified by considering quittor under two headings only--namely, 'Simple or Cutaneous' and 'Sub-horny,' and discussing the other varieties as simply complications of either of these two. 1. SIMPLE OR CUTANEOUS QUITTOR. _Definition_.--This condition is simply a sloughing of a portion of the skin of the coronet, together with a portion of the immediately underlying soft structures.