Upham.] 
134 
[Dec. 19 
frequent ; Astarte undata , rare ; and a columella, perhaps of Clirys- 
odomus decemcostatus. In the third column are the species found 
in the cliff of Moon island ; in the fourth column, those obtained 
from the well at Fort Warren ; in the fifth, those of Peddock’s 
island ; and in the sixth, those of the northern cliff in Hull. At 
the other localities only Venus mercenaria was found in the lim- 
ited time available for search. 
All these species, which remain from the marine fauna that ex- 
isted before the formation of the last ice-sheet upon this area, 
excepting one whose determination is doubtful, are found living at 
the present time in the adjoining waters of Massachusetts bay. 
Stimpson wrote of his collection: “With the exception of Venus 
mercenaria , I have obtained all of them in a living state by dredg- 
ing within a mile of the locality where they are now found fossil.” 
Nor are any noteworthy differences observable between these fos- 
sils and the living shells, excepting that the Venus mercenaria 
belongs, like most of the fossils of this species in Sankoty Head, 
Nantucket, to the very massive and strongly sculptured form, 
probably not to be regarded as a distinct variety, which still sur- 
vives in the waters of Nantucket . 1 . 
Four species in this list attain their southern limit at Cape Cod ; 
and one, Tapes Jluctuosa , is not reported south of Nova Scotia 
and the Fishing Banks. The remaining sixteen have a southward 
range beyond Cape Cod. In northward range, five extend only to 
the Gulf of Saint Lawrence ; and three of these, namely, Urosal- 
pinx cinerea, Venus mercenaria , and Ostrea Virginiana , occur only 
in isolated colonies north of Massachusetts bay. Another, Astarte 
castanea , has its northern limits on the coast of Nova Scotia and 
at Sable island ; while the burrowing sponge, Gliona sulphurea , is 
not reported beyond Portland. Fourteen are more boreal, of 
which four continue to Labrador, and ten to the Arctic ocean. 
The great abundance of the round clam, Verius mercenaria, which 
is now scarce in Massachusetts bay but plentiful south of Cape 
Cod, with southward range to Florida, indicates that the sea here dur- 
ing part of the epoch just preceding the last glaciation was warmer 
than at the present time . 2 Similarly, the colonies of this and asso- 
1 Am. Journ. Sci., ill, vol. x, 1875, pp. 369, 371. 
2 From the same evidence and the presence of other species elsewhere in the Pleisto- 
cene deposits of the eastern United States north of their present range, Desor announced 
in 1847 to the Geological Society of France (Bulletin, Yol. v, p. 91) and in 1852 in the 
American Journal of Science (II, vol. xiv, pp. 52, 53) that a warmer climate then pre- 
vailed throughout this whole district. 
