76 PROCEEDINGS: BOSTON SOCIETY NATURAL HISTORY. 
Cakile edentula (Bigel.) Hook. Common on the sea strands 
and along tJie l)rackish beach of Wallace Lake. ./. Macouti: II. T. 
Uiissow (E); //. .S7. John, no. 1,241 (H). 
FL, i'V.^August. 
Raphanus sativus L. Established at the Main Life Saving Sta- 
tion. //. iS^. John, no. 1,242 (H). 
Fl. — August. 
Brassica arvensis (L.) Ktze. A weed near the Life Saving Sta- 
tions. ,/. Maconn; II. St. John, no. 1,243 (H). 
FL — August. 
Sisymbrium officinale (L.) Scop. A weed near Life Saving 
Station, No. 3. //. St. John, no. 1,244 (H). 
FL, Fr. — September. 
DROSERACEAE. 
Drosera rotundifolia L. Common in the wet dune hollows and 
on the margins of the fresh-water ponds. J. Macoun; H. T. Giissow; 
H. St John, no. 1,245 (H). 
FL, Fr. — August. 
D. longifolia L. In wet sand and bogs, found only by J. Macoun 
(C. no. 21,187). 
FL — August. 
CRASSULACEAE. 
Tillaea aquatica L. Forming pure mats at the wet borders of 
the fresh-water ponds. ./. Maconn (C. no. 21,156); H. St. John, 
nos. 1,246 and 1,247 (H). 
FL, Fr. — July and August. 
The three collections of this plant from Sable Island show, in the 
same clump, plants which have "nearly sessile" flowers and fruit, 
and other plants bearing nearly sessile flowers in the upper axils and 
peduncled ones in the lower axils. According to our present Ameri- 
can treatments, we should have to recognize in these apparently 
pure clumps two species. An examination of the American material 
of Tillaea Vaillantn Willd. shows that in every known locality T. 
aquatica occurs and occurs more abundantly, that its characters are 
a matter of degree, not strictly definable. Consequently the author 
feels that T. Vaillantii of American authors should be treated as 
identical with T. aqvatica. The inference must not be drawn that 
