32 Rhodora [FEBRUARY 
The distribution of the pond-plants, in common with that of the 
rest of the flora, is influenced to a considerable extent by the topog- 
raphy of Cape Cod. The “backbone of the Cape" is formed by two 
fan-shaped terminal moraines, one of them of rather low hills running 
north and south along the eastern shore of Buzzard’s Bay and string- 
ing out into the Elizabeth Islands; and the other, with slightly higher 
elevations, which sometimes reach nearly 300 feet, extending east 
and west down the north shore of the main body of the Cape. East 
and south of these moraines, respectively, the country is mostly 
barren sand-plain from the soil of which practically all the fine material 
was washed by the waters flowing from the glacial ice-front; while 
on the narrow strips of land on the other side of the hills, in each case, 
and between them and the water, the country is much more fertile. 
This is particularly noticeable on the north shore of the Cape, in the 
northern parts of the towns of Sandwich, Barnstable, Yarmouth and 
Dennis, where there is considerable clay in the soil, deposited on the 
bottom of a dammed-up glacial lake or scooped up by the ice-sheet 
from the bottom of the bay. In these richer strips muddy drained 
ponds and alluvial swamps are conspicuous, while the typical sandy 
ponds, with their coastal-plain vegetation, are practically confined 
to the above-mentioned barrens and to the very sandy “forearm,” from 
Chatham to Provincetown. 
Although conditions are very similar throughout these sandier parts 
of the peninsula, the pond flora, in common with the rest of the vegeta- 
tion, grows less varied as one goes eastward " down" the Cape. Of 
course the commonest and most characteristic plants (with one or two 
exceptions, such as Stachys hyssopifolia, which apparently does not 
occur below Brewster) are nearly universal in their distribution, but 
many of the less common things stop somewhere on the upper (west- 
ern) part of the Cape. Sabatia dodecandra, for example, gets as far as 
Eastham, but the smaller species, S. gracilis, together with such plants 
as Scleria reticularis and Fuirena squarrosa reach their eastern limit 
on the group of small ponds near the Barnstable-Yarmouth line. 
Crotolaria, in the same way, does not come east of the town of Sand- 
wich. 
This central part of the Cape, including the towns of Sandwich, 
Barnstable and Yarmouth, has by far the richest pond-flora in the 
county. Snake, Peter’s, Triangle and Spectacle Ponds, in Sandwich 
have wide sandy beaches and a large flora which, together with their 
