Above the lighter-colored clay just mentioned was a foot of a clay which contained wood and roots, the unused portion of the brick clay that once existed there, but which had been removed for the manufacture of bricks.
Inasmuch as the clay overlying the bed in which the remains were found contains marine shells, it is certain that since their deposition the land has been considerably elevated.
George N. Stone (Monogr. XXXIV, U. S. Geol. Surv., pp. 286–291) has discussed the age of the glacial deposits at Portland. Professor M. L. Fuller has written to the author that on the Maine coast the chief clay is known as the Leda and is found at Portland and Gardiner, and that it probably antedates the Wisconsin. This is not to be correlated with the Leda clay of the St. Lawrence Valley. It corresponds rather to Clapp’s “high-level clays” (Bull. Geol. Soc. Amer., vol. XVIII, p. 505, seq.).
11. _Jeffries Reef, off Portsmouth._—The specimen from this place consists of the greater part of the left side of the skull of a large individual. The occipital and the exoccipitals are missing. The bone and especially the tusk have suffered some decay. The fragment is labeled as having been dredged from a depth of 50 to 75 fathoms on Eastern Jeffries Reef. The bottom was hard. Jeffries Reef lies 5 or more miles off the southernmost part of the Maine coast and extends from the Isle of Shoals to Boon Island. The skull belonged to an old individual. The length from the rear of the mastoid process to the front of the premaxilla is 360 mm. The exserted part of the tusk measures 225 mm. in length. At its base the diameters are 65 mm. and 42 mm. There are 4 large grinding teeth. There is no reason for supposing that the species represented is not _O. rosmarus_.
12. _Gay Head, Martha’s Vineyard._—In his “Travels in North America,” volume I, 1845, page 257, plate V, figure 1, Lyell announced the finding of a part of a skull of a walrus at Gay Head. This he had purchased from a fisherman who lived there and who said it had fallen out of a conglomerate found at that place and which contains bones of cetaceans. The skull retained but a small portion of its animal matter. Richard Owen, to whom the skull was shown, regarded it as belonging to a species distinct from _O. rosmarus_. The upper jaw contained the base of one tusk, the socket for the other, and 3 molar teeth on each side. The reduced number of molars furnishes no distinctive character, for existing individuals sometimes present this number. The base of the tusk has its transverse diameter greater than usual relatively to the fore-and-aft diameter. According to Lyell’s illustration of the specimen, the greater diameter was 70 mm., the shorter 53 mm. The writer has seen no tusk of _O. rosmarus_ as thick as this; but the thickness is variable and may possibly attain to two-thirds of the greater diameter.