157 



Family XIII. — ProtococcaceiE. 



7. Scenedesmus obtusus, Meyen., p. 173, PI. CLVL— Found 

 in a gathering made from a small pool near the Penobscot, and 

 which stood for two months in the laboratory before it was ex- 

 amined. Plentiful. Oct. 



8. Sciadium arhuscula, A. Br., p. 174, PI. CLVII. — Two or 

 three specimens observed in the water of the old well. The 



specimens invariably had eight rays in the umbel and were 

 simple. 



Family XVI. — Palmellaceae. 



9. Dictyosphm-hmi reniforme, Bulnh., p. 186, PI. CLVI. 

 Quite plentiful in a pool near the Penobscot, opposite Great 

 Wor"ks, collected by Mr. L. H. Merrill. 



10. Glceocystis ampla, Kg., p. 196, PI. CLXVI.— Common in 

 standing water about Orono. Pool near Penobscot at Great 

 Works (Mr. L. H. Merrill). 



11. RapJiidium polymorpJmm, Yxq?>.,vax. co7itorUwi (Thur.), 

 Wolle, p. 198, PI. CLX.— Rather common in pools and small 

 ponds near Orono. 



12. EremosphcBra viridis, D, By., p. 200, PI. CLXVII. 

 Very abundant in a gathering made near Great Works by Mr. 

 L. H. Merrill. 



Specimens, shedding the membranous envelope, undergoing 

 fission and forming reddish brown resting spores, were observed. 



Family XVL — Conjugatas, 



^3* Zygnema uisigne, Kg., p. 223, PI. CXLIII. — Common in 

 small spring brooks and ponds. Finely in copulation. Oct 



14- Zygnema anomahnn (Hass.), Kg., p. 224. This in- 

 teresting form was collected in abundance in a small spring 

 pond near Orono by Roy Harvey. The colorless gelatinous 

 sheath soon after gathering is liable to become almost invisible. 

 Filaments with sheath, in our specimens, measured 40 )a\ with- 

 out sheath, 22 /<. The specimens wxre all sterile, though col- 

 lected from a spring in December, after the pond had been frozen 

 for two months. They were in fine vegetative condition. 



pectinatnm 



Abun- 



