138 FRESH-WATER ALGJ3 OF THE UNITED STATES. 



Fig. 12, pi. 21, represents the front view of an empty half frond of this species, 

 magnified 450 diameters; fig. 12 a, the side view of an empty frond. 



E. afflne, RALFS. 



E. E. humerosum affine, paulo minus ; semieellulae quinquelobae ; lobi basales quales in E. hume- 

 rosum sed tumores quatuor in seriem transversam siraplicem dispositi, lobi interruedii valde 

 abbreviati eorumque basi tumoribus duobus instruct!, lobus polaris magis porrectus ct in 

 apice minus dilatatus; cytioderma subtilissime punctatuin sublaeve. (R.) 



Long. 0.0038" 0.0041". (R.) 



Syn. E. affine, RALFS, British Desmidese, p. 82. 



Hab. South Carolina ; Georgia ; Bailey. 



Frond about twice as long as broad ; segments 3-lobed ; basal lobes slightly emarginate, 

 having intermediate between them and the end lobe on each side a tubercle representing 

 middle lobes, the upper margin of which is horizontal ; end lobe exserted, dilated, its notch 

 linear. 



Empty frond ; f. v. minutely punctate ; the segments with four basal inflations, two above and 

 two on end lobe ; tr. v. elliptic, with four inflations on each side and one at each end ; e. v. 

 end lobe emarginate at opposite ; e. v. end lobe emarginate at opposite external margins, 

 producing four shallow lobulets. (A.) 



E.Didelta, (TURPIN) RALFS. 



E. robustum, diametro duplo longius etiam supra, in sectione transversa ellipticum, ambitu un- 

 dulato-crenatum, in utroque latere crenis quaternis ; semicellulis pyramidalibus, quinquelobis, 

 tumoribus 9 in series tres alternantibus ordinatis, lobis inferioribus oblique truncato-rotundatis 

 nonnunquam leniter retusis, intermediis subadscendentibus, rotundatis, lodo polari minus 

 dilatato, bifido, segmentis rotundato-truncatis, conniventibus, in apicc tumidis ; cytiodermate 

 distincte punctate, punctis modo irregulariter sparsis modo in seriebus rectis collocatis. (II.) 



Long. 0.0055". Lat. 0.002Y9". 



Syn. E.Didelta, (TURPIN) RALFS, British Desmidese, p. 84. 



Hab. South Carolina; Georgia; Rhode Island; Bailey. Pennsylvania; "Wbod. 



Frond rather more than twice as long as broad ; segments pyramidal, inflated at the base and 



again at the middle, end scarcely dilated, rounded, its notch linear. 

 Empty frond punctate ; f. v. segments with several inflations in lines and two at the end ; tr. v. 



elliptic with four inflations at each side and one at each end ; e. v. end lobe entire at margin. 



Sporangium orbicular, with subulate spines. (A.) 



Remark. Fig. 13, pi. 21, represents this species. 



E. ampullaceum, RALFS. 



E. diametro dnplo longius ; semicellulis trilobis, ad basin tumidis, e basi latissima subito in lobi 

 polaris collum attenuatis, lobis basalibus maximis integris, loco loborum intermediorurn pro- 

 cessu deutiformi, lobo polari cuneato, in apice bifido, segmentis late truncato-rotundatis; 

 cytiodermate subtiliter punctate. (R.) 



Long. 0.0035" 0.0038". Lat. max. .0026" ; lat. in colli (lobi polar.) 0.00085". (R.) 

 Syn. E. ampullaceum, RALFS, British Desmideae, p. 83. 

 Hab. South Carolina ; Florida ; Bailey. 



Frond rather more than one-half longer than broad ; segments obscurely 3-lobed, short, with 

 broad inflated base ; basal lobes not emarginate, having on each upper side a small inter- 

 mediate tubercle between each and the end lobe ; end lobe exserted and dilated, its notch 



