The “Irish Elk” has been hitherto only found in the shell-marl underlying extensive turbaries. It is a true deer, intermediate between the fallow and rein-deer. In England it has been found in lacustrine beds, brick-earth, and ossiferous caves (Owen). The subject of the present paper is a dorsal vertebra belonging to a skeleton quite as large, if not larger than the specimen in the College of Surgeons Museum, London, with which it was compared. It was found on the Shirly property, in a bed of gypsum, county of Monaghan, Ireland. This gypsum-bed is very extensive, being many square miles in extent, underlying the glacial drift, embedded in and. sometimes alternating with a fine ferruginous clay. The subjacent rock is the older or lower coal sandstone, which lies unconformably on the mountain limestone, which reposes on the Silurian, the latter forming hills of 500 or 600 feet elevation in the immediate neighbourhood. The surface-soil is formed of ancient drifts of different ages, the one containing enormous blocks of mountain limestone, the other, the older, more compact, and containing small fragments, very rare, of a limestone, which, from comparison, is supposed to have been brought from the counties of Tyrone and Fermanagh, by a current that denuded all the western aspects of the Greywacke ranges of hills, producing very markedly the phenomena of “crag and tail,” which are there to be seen in endless examples.