FRESn-WATER A L G .E OF THE UNITED STATES. 99 



Coenobiura mobile, globose, subglobose or in square tables, composed of green colls which have 

 two motile cilia and a double contractile vesicle. The common tegument surrounding the cocnobium 

 hyaline, and more or less amplified. 



Propagation either se.xnal or non-sexual. The sexual monaseious or dia3cious; either all or some 

 of the cells of the coenobium exhibiting male and female characters. The male cells containitig 

 spermatozoids, the female finally converted into a quiet oospore. Non-sexual propagation taking 

 place l)y means of motile gonidia (both niarrogonidia and niicrogonidia, by some called zoogonidia). 

 Macro- and micro-gonidia arising by the simultaneous and repeated division of the cytioplasm ; the 

 first definite in number (2-4-8-1 G, &c ), the larger, oblong or rounded, with the anterior end more 

 or less rostellate, with two cilia exsertod through the membrane of the vesicle, furnished with a cen- 

 tral or parietal red spot, and often with two contractile vacuoles; the niicrogonidia indefinite in 

 number, much the smaller, pale or dirty green or luteolous, furnished at the apex with cilia, mostly 

 even within the mother-cell, moving rapidly, and finally escaping on the rupture of tlie membrane. 



Genus CHLAMYDOCOCCUS, A. Braun. 



Cellulse globosiE, vel subglobosae (4—8 in coenobium fugacissimnm conjuncta;), cytiodermate sub- 

 crasso firmo, cytioplasmate granuloso, fusco-rubro vel puniceo (in evolutionis gradibus quilmsdam 

 in colorem viridem mutato). Macrogonidia 2-4-8, rotundata, polo antico rostrifornii producta, duo 

 cilia longissima gerentia, nucleo centrali rubro, globulis amylaceis 4-6, non semper visibilibus 

 instructa, tegumeato amplissimo hyalino plerumque ovoideo vestita. Microgonidia niulto minora, 

 numerosa, luteola vel sordide viridia, apice rubella, ciliis binis instructa, intra tegumentum matri- 

 cali alacriter vacillantia, denique membranae ruptura elabentia. (R.) 



Cells globose, or subglobose (4-8 conjoined in a very fugitive coenobium), cytioderm thickish, 

 firm, cytioplasm granular, brownish-red or puniceus, in certain stages of evolution ciiangid into 

 ^reen. Macrogonidia 2-4-8, rounded, the frond end bearing very long cilia, furnisljid with a 

 central reddish nuclei and with four to six, not always perceptible, starch granules, clothed with a 

 very ample, hyaline, mostly ovoidal tegument. Microgonidia much the smaller, numerous, luteolous 

 or sordid green, the apex reddish, furnished with two cilia, moving actively within the maternal 

 '.egument, and at last escaping by the rupture of the membrane. 



Ch. nivalis (Bauer, Ag.). A. Braun. 



Ch. globulis, 0.004"— 0.00135". (R.) 



Hab. — In nive aitcrna, Greenland. Rocky Mountains. 



Syn. — Ch. nivalis (Baur, Ag.). A. Braun. Rabenhorst, Flora Europ. Algarum, Sect. III. 

 p. 97. 



Globules, 0.004"— 0.00135" in diameter. 



Remarks. — I have never seen any good specimens of tliis plant, merely some 

 cells mounted in Canada balsam, and therefore ruined for scientitic study, whicli 

 had been collected by Dr. Kane in one of his Arctic voyages. I have also had 

 some indications of plants in a little parcel sent me by Mr. Sereno Watson, who 

 informs me he has seen the red snow very abundant in the higher peaks of the 

 Rocky Mountains. It is a matter of presumption rather than determination, there- 

 fore, that the snecies is identical with the European. 



Genus VOLVOX, Ehkb. 



Coenobium exacte sphasricnm, continuo rotatum et agitatum, globum cavnra qnasi fingens, e cel- 

 lulis numerossissimis SBquali distantia peripherice dispositis, gelatina matricali connexis, ])uncto 

 rubro laterali, locellis (vacuolis) binis contractibilibus necnon ciliis binis longe exsertis instructis, 

 vesica communi hyalina eircumcinctis compositum. 



