In his admirable essay on the Devonian Fishes, in the Tenth Decade of the Geological Survey, Professor Huxley has clearly indicated and described the differences and the resemblances of the genera Holoptychius and Glyptolepis. In the interesting work of the Rev. Dr. Anderson on ‘Dura Den,’ in which its exquisitely-preserved fossils are described, no mention is made of Glyptolepis. In the November part of the ‘Journal of the Geological Society of London,’ Mr. Powrie lias called attention to the occurrence of Glyptolepis in slabs recently disinterred, for the St. Andrew's Museum, from Dura Den. Through the kindness of Dr. Anderson, a slab was presented to the Montrose Museum in 1859; and it is now apparent from it that Glyptolepis is not of rare occurrence at Dura Den, and that either this genus has been passed over altogether, or confounded with Holoptychius. The fishes in the Montrose Museum are smaller, and do not in all points correspond with those described by Mr. Powrie, but we think they emphatically demonstrate that the Holoptychius Flemingii must now be denominated Glyptolepis.

On the slab in the Montrose Museum there is one fine specimen of Holoptychius and six specimens of Glyptolepis, not regarding fragmentary portions of fishes. At the first glance there is a resemblance in size, in general aspect, and outline, among the fishes. Their average length is about nine inches, and their breadth at the thickest part of the body nearly three inches.