138 TUFTS COLLEGE STUDIES, VOL. II, No. 3 



3. INEFFIGIATA W. and G. S. West, 1897, p. 513. 



Cells, ellipsoid or ovoid, with parietal chromatophore (and 

 pyrenoid ?) often colored brick-red, united in spherical or sub- 

 spherical families, the cells superficial ; each family surrounded 

 by a tough, elastic membrane, with various irregular folds, 

 lobes, processes and spines, the older membrane often including 

 several generations of families ; asexual reproduction by cell 

 division, the families separating as they become too large. 



The cells have considerable resemblance to those of Botryo- 

 coccus Braunii ; the aggregations are more complex, the outer 

 membrane seems quite distinct from anything found in Botryo- 

 coccus, but until we know more of the life history of the two 

 forms, their distinctness is open to question. 



I. NEGLECTA W. and G. S. West, 1897, P- 53 >' I 93, P- 80, 

 PI. CCCCXI/VII, figs. 1-6. Cells 3-5X6-10 p.; families 20-50 M 

 diam.; aggregations of successive families up to 350 p.. In 

 standing water. Fig. 25. Me., Mass. Europe. 



4. TETRASPORA Link, 1809, p. 9. 



Colony (frond) gelatinous, membranaceous ; saccate, tubular 

 or plane ; containing globose cells in a single layer, scattered 

 more or less in 2s and 43, the thick cell wall diffluent into the 

 general membrane. Asexual reproduction by successive divis- 

 ion of cells in the plane of the membrane ; also by cells becoming 

 ciliate and motile ; they later come to rest, lose their cilia, form 

 a gelatinous membrane, and divide by 2s and 43 ; also by akin- 

 etes. Sexual reproduction by the conjugation of small, biciliate 

 gametes, produced 8 in a cell, the zygospore germinating at 

 once. 



A genus in which quite a number of species have been de- 

 scribed, some of them not very sharply distinguished. They 

 are all fresh water plants, and are very common in brooks and 

 pools. 



KEY TO THE SPECIES OF TETRASPORA. 



I. Frond cylindrical at all ages. i. T. cylindrica. 



I. Frond cylindrical only when young, if ever. 2. 



2. Frond an irregularly inflated sac. 3. T. gelatinosa. 



2, Frond at first tubular, but soon splitting into irregular segments, 



often much perforate. 2. T. lubrica. 



i. T. CYLINDRICA (Wahl.) Agardh, 1824, p. 188; Kiitzing, 



i849a, PI. XXX ; Wolle, 1887, p. 190, PI. CLXV, figs. 7 and 



8; P. B.-A., Nos. 908, 1510. Frond attached, up to one meter 



long, seldom more, up to 2 cm. diam., cylindrical, unbranched, 



