152 FRESH-WATER ALGJE OF THE UNITED STATES. 



curved. More rarely only one, or more than two oogonia. 

 Mature oospore spotted with brown, sporoderm colorless, 

 composed of three strata. Filaments variable in size, 50- 

 125 jJi in diameter. Oogonia vary in proportion. Asexual 

 propagation by gonidia distributed by decay of the cell- 

 membrane. 



Var. KACEMOSA, Walz. 



Oogonia shortly pedunculate, 3-5, sometimes 8-10, aggre- 

 gated in a corymbose manner. Antheridia single, scarcely 

 longer than the oogonia. 



Syn. Ectosperma geminata, Vauch.; Vaucheria Dillwynii, Rab. ; 

 Vauch. ovoidea, Hass. ; Vauch. ovata, Gray ; Ectosperma 

 ovoidea, Huds. 



In stagnant waters, ditches, ponds, etc. 



Frequently peculiar appendages known as Vaucheria galls 

 occur on filaments of this and other species ; somewhat urn- 

 shaped excrescences, cylindrical cells, outgrowths of the 

 plants; swollen below the middle, contracted at the base 

 and distended at the truncate apex. They measure 200- 

 350 fj- in diameter, length three times greater. These are 

 Rotifer nests produced probably by a sting or other irrita- 

 tion. The living creature is always seen in proper season 

 near the bottom of the cell together with 10-20 or more, dull 

 rose colored eggs. Rotifers (?) frequently make a home in 

 the filaments of Vaucheria. G. Benko calls the parasite 

 Notommato Werneckii. 



Plate CXXVIII, figs. 1, 2, 3, parts of plants of true V. 

 geminate, ; figs. 4, 5, forms of variety racemosa from speci- 

 mens from Iowa and Pennsylvania ; fig. 6, an abnormal but 

 not rare form of fruiting; fig. 7, a gall, or Rotifer's nest. 



VAUCHERIA HAMATA, (Vauch.) Lyngb. 



Aquatic or terrestrial, thallus rather rigid, vaguely 

 branched. Oogonia single or double, seated on short seg- 

 ments of the divided end of branchlets ; when two oogonia, 

 then a third intermediate segment develops the antheri- 

 dium, which elongates and recurves. Mature oospores are 

 involved in a sporoderm, formed of three or four membranes. 



Syn. Ectosperma hamata, Vauch. ; Vaucheria hamulata, Kg. 



The only satisfactory specimens hitherto discovered are 

 from California. 



Plate CXXVIII, figs. 8-10, drawn from California speci- 

 mens ; single and twin oogonia. 



