SPHAEROZOSMA. 29 



s. nil hrum, Bailey. Plate IV. figs. 1, 2. 



Cells twice as broad a- long, deeply incised on each side, 

 end- rounded, junction margin straight, filaments twisted, fre- 

 quently enclosed in a gelatinous envelope. 



Diameter 60-82 >>. 



Var. planum, Wolle. Plate IV, fig. ">. 1. 



Similar t<> typical form, except in size and in the absence of 

 the tw isl in the filaments. 



Diameter 30-38 . 



Var. ini i \ Tim. Wolle. Plate X LI X. fig. 8. 



I infers from the preceding in the central inflation, producing 

 a shoii isthmus between the cells. 

 I iameter 38 ". 



The typical form appears to be widely scattered throughou I 

 many States: Rhode [aland, Massachusetts, Pennsylvania, 

 \.v, Jersey, South Carolina and Florida. The variety 

 planum I found in a trench a.idethe Rail Knad near Metuchen, 

 \ .1. The water w n with the abundance of it The 



variety injiatvm occurs Bpareely in ponds of New Jersey. 



S. FILIFORME, Pale Plate IV, figs. 5, 6. 



( Jells about as long as wide, constricted in the middle with 

 a deep, acute incision; ends of lobes rounded, connected by 

 two sessile glands. 



Diameter 1 2- 1 8 u. 



Pond water- of Pennsylvania and New Jersey. 



General appearance very near 8. pulchrum variety, but 

 smaller, and length of cells equal to the diameter. Did not 

 observe a gelatinous Bheath mentioned by Rabenhorst; 



Kirchner admits do sheath. Fig. ' is very near Corda's 8. 

 lotto Uifi nun. 



S. EXCAVATUM, Rails. Plate IV, figs. 8, 9, 10-12. 



( Jells twice as long as broad, with a deep, wide sinus on each 

 side, connected by two small sessile glands. 

 Diameter 912 >>.. 



Not infrequent in ponds; sometimes it occurs with, and 

 sometimes without, the gelatinous sheath. 



