42 | Rhodora (Мавсн 
strongly under-arching hyaline cells.— Massachusetts, 16 Sept., 1891, 
leg. Faxon. 
This species may be distinguished from Sph. cuspidatum by the 
very narrowly margined branch leaves, from Sph. angustilimbatum 
by much smaller stem leaves which are not fibrillose to the base, and 
which have the margins broadened below, as well as by the mostly 
three-branched fascicles with equally divergent branches. 
FRIEDENAU, 25 Feb. 1908. 
NOMENCLATORIAL CHANGES IN ISOËTES.— ISOËTES MACROSPORA 
Dur., var. heterospora, comb. nov. Isoëtes heterospora А. А. Eaton 
appears to be a form of Г. macrospora Dur., endemic in streams and 
ponds on Mt. Desert Island. The vegetative parts of the two appear 
to be practically identical, differences being confined to the spores, 
which vary greatly in size and markings in the Mt. Desert plants. 1 
therefore think it proper to reduce I. heterospora to the rank of a variety 
of І. macrospora. 
I. DopaE: A. A. Eaton, var. Robbinsii, comb. nov. Іп compliance 
with Art. 49 of the Vienna Code the name 1. Dodgei must be restored 
to the species designated by Engelmann as Т. riparia, var. canadensis 
(1. canadensis A. A. Eaton), since it is the earliest name of the plant 
in its present rank. It becomes necessary, therefore, to change 1. 
canadensis, var. Robbinsii to I. Dodget, var. Robbinsii.— А. A. EATON, 
'The Ames Botanical Laboratory, North Easton, Massachusetts. 
A SOUTHERN FLORA AND FAUNA OF POST-PLEISTO- 
CENE AGE IN ESSEX COUNTY, MASSACHUSETTS. 
JoHN Н. SEARS. 
Tus paper is the result of special studies upon a fossil or ancient 
marine molluscan fauna, collected in estuaries and bays on our coast, 
with a view to explaining the presence of certain plants of a southern 
flora found growing today in Essex County, Massachusetts, and 
elsewhere near the coast of New England. The data and conclu- 
sions of the paper may be stated under three headings. 
