1909.] NATURAL SCIENCES OF PHILADELPHIA. 393 



half a mile long, and its banks have been sodded, the undergrowth 

 has been removed and the tree vegetation, notably Pinus rigida, has 

 been left, giving a park-like aspect to the surroundings. The authori- 

 ties periodically clear the lake of all vegetation, in order to provide 

 for the water carnivals which are held some time during the summer 

 months. But yet the vegetation grows almost as rapidly as it is 

 removed, and constant vigilance must be exercised to prevent the 

 filling of the shallow lake basin. The most persistent of these plants 

 is Potamogeton perfoliatus, which forms extensive associations here 

 and there in the quieter portions of the lake. Another persistent 

 plant is Elodea (Philotria) canadensis, which grows so fast as to choke 

 portions of the lake. Upon this aquatic plant grow epiphytically, 

 according to a study of microscopic material collected in the summer 

 of 1908, a blue-green alga, Mastigonema sejunctum, which lives in tufts 

 or soft mosses on the leaves of Elodea, as also a diatom, Gomphonema 

 constrictum. The filaments of Mastigonema are rather rigid, straight 

 and spuriously branched, and their apex is delicately hair-like, while 

 heterocysts are found at the base of each of the branches. The diatom, 

 Gomphonema constrictum, has wedge-shaped frustules in the girdle- 

 view, and in the specimens studied they were attached by their inferior 

 smaller extremities to a system of hyaline threads that form bound 

 together a stalk, which attaches them to the Elodea leaf. The fresh 

 water plankton of this lake was found to consist in September, 190S. 

 of Spirogyra crassa (which lives over the winter), Anaboena flos-aquv 

 var. circinalis and Scenedesmus obliquus. The water silk, Spirogyra 

 crassa, formed floating masses near the shore (found by me also in April, 

 1909), while Anabama flos-oqim var. circinalis about the end of August 

 was in such abundance as to suggest "the flowering of the mere." 

 Its beaded filaments formed most beautiful coils or spirals. 



Como Lake. — Como Lake will be treated in a few years like those at 

 Asbury Park and Ocean Grove, as the building of summer houses is 

 fast approaching it, so that these observations will preserve to botanic 

 posterity the only statement as to the original flora which surrounded 

 it. Following the south shore first, we can recognize four strips of 

 plants, viz. : (1) the water strip; (2) the wet ground strip ; (3) the dry 

 ground strip ; (4) the forest strip. The first two strips are practically 

 the same, because the vegetation of the wet soil encroaches upon the 

 water surface. The west shore is somewhat gravelly and sandy, and 

 here I found, beginning at the western end of the pond and walk- 

 ing eastward, the following characteristic plants: Agrostis hyemalis 

 ( = A. scabra), Polygonum sagittatum, P. acre, Cyperus erythrorhizos 



