38 CONNECTICUT GEOL. AND NAT. HIST. SURVEY. [Bull. 



are sometimes found in a single cell. Biciliated gametes are 

 also found which conjugate. 



P.sp. (?),Fig. 65. 



P. pertitsum Kutz., Figs. 66, 68, 70, 71. 



P. pertusum var. clathratum A. Br., Figs. 50, 52, 57. 



P. tetras Ehrb., Fig. 69. 



P. Boryamtm (Turp.) Menegh. var. granulatum Kutz., 

 Figs. 58, 59, 67. 



P. Ehrenbergii A. Br., Figs. 61, 62, 63, 64. 



SUB-FAMILY II. HYDRODICTYF^E. 



Plants large, composed of a number of large cells, which 

 are so arranged as to form a net. Zoogonidia swarm and be- 

 come quiescent within the mother-cell, and there unite to form 

 new ccenobia. 



Hydrodictyon Roth. Ccenobium large, composed of 

 oblong cells joined at the ends, forming a reticulated stratum, 

 at first baggy, then net-like. All the cells are fertile, breaking 

 up to form large numbers of microgonidia within the mother- 

 ccenobium. After a period of activity they come to rest and 

 form a new ccenobium by joining together at their extremities. 

 Sometimes they become perfectly dry ; but, when moistened, 

 they form biciliated macrogonidia which join themselves into 

 daughter-ccenobia within the mother-cell. Motile gametes are 

 also found which become free and conjugate into a globose 

 zygote. The only known species is the following: 



H. reticulatum (L.) Lag., Figs. 215, a, b, c. 



FAMILY IV. PLEUROCOCCACE.E. 



Plants mostly unicellular, sometimes composed of short, 

 creeping, slightly branched filaments, which are never atten- 

 uated to hairs. The cell walls are generally very firm, and the 

 cells aggregate to form indefinite colonies. Multiplication by 

 division in two or three directions. Asexual reproduction 

 sometimes by means of biciliated zoogonidia. Of the six 

 genera of this family we have found only one. 



Pleurococcus Menegh. (Protococcus Ag., in part; 

 Cystococcus Nag. ; Chlorococcus Fries, in part ; Pseudo- 

 pleurococcus Snow). The cells are usually globular, some- 

 times angular from pressure. Division occurs in three direc- 



