FRESH-WATER ALG.E OF THE UNITED STATES. 137 



Long. 0057"— 0.0065". Lat. max. 0.00346". 



Syn. — E. oblongum, (Greville) Ralfs' British Desmidiese, p. 80. 



Hab. — Rhode Island ; Bailej. 



Frond rather more than twice as long as broad, smooth, oblong; segments 5-lobed; lobes nearly 

 equal, cuneate ; lateral lobes, or the Ijasal only, with a broad, shallow, marginal concavity, 

 all their angles rounded, terminal noteli linear. 



Empty frond; f. v. seg. punctate, with three large inflations, on surface near the base, two 

 others above and two on terminal lobe; tr. v. three times as long as broad, with three sul- 

 distant marginal inflations at each side, and one at each end, in /3, broader in proportion, 

 more elliptic, and inflations close; e. r. end lobe notched at opposite external margins. 

 Sporangium orbicular, beset with numerous conical tubercles. (A.) 



B. Lohi polares evidenter discreti ct in apice anguste incisi. 



B. End lobes evidently separated and narrowly incised in the centre. 



E. crassuni, (Breb.) Ktz. 



E. oblongum, dianietro subtriplo longius, profuude constrictum, sinu angusto lineari, e vertice 

 subquadrangulare, utroque polo profunde e.xcisum, angulis rotundatis ; seuiicellulis (fronte) 

 trilobis, basi et in quoque angulo tuniore instruetis, lobis lateraliljus latissimis unisinuatis, 

 lobo polari panllum prominente, in apice bifido, segmentis late rotundatis; cytiodermate dis- 

 tincte punctato, punctis in series transversas ordinatis. (R.) 



Long. 0.0051"— 0073". Lat. mas. 0.0041". (R.) 



Syn. — E. crassum, (Brebisson) Kltzing Rabenhorst, Flora Europ. Algarura, Sect. III. 



p. 181. 

 Uab. — United States. 



Frond about twice as long as broad, subquadrilateral, smooth; segments 3-lobed ; basal lobes 

 very broad, with a very broad, shallow marginal sinus, in which there is sometimes a slight 

 intermediate rounded projection ; end lobe creueate, rounded, terminal notch linear. 



Empty frond ; f. v. punctate, segments with three inflations below and two above ; tr. v. two or 

 three times longer than broad, with three lobes or inflations at each side and one at each end ; 

 e. V. end lobe sinuate at opposite external margins. (A.) 



E. oi'iiatiiBii, Wood. 



E. oblongum, diamctro duplo longius, profunde constrictum, sinu angusto lineari ; semiccllulis 

 a fronte trilobatis; lobis basalibus latissimis, nonniliil sinuato-emarginatis, angulis plus minus 

 productis ot rotundatis; lobo polari medio profunde lineare iiiciso, segmentis late rotundatis; 

 semicellulis a latere bilobatis, lobis basalibus profunde emargiuatis et cum angulis plus minus 

 acutis ; cytiodermate distincte ordinatim punctato. 



Diam.—jJ'^^js" = .00029". 



Syn.—E. ornatum, Wood, Proc. A. N. S., 1869. 



Hab. — Saco Lake ; Xew Hampshire. Lewis. 



E. oblong, twice as long as broad, profoundly constricted ; semicells from the front trilobate ; 

 basal lobe very broad, slightly sinuately-emarginate, angles more or less produced and 

 rounded ; polar lobe mediauly profoundly linearly incised, segments broadly rounded ; semi- 

 cells bilobate at the sides, basal lobes profoundly emarginate and with the angles more or 

 less acute ; cytioderm distinctly regularly punctate. 



Remarl-s. — This species is close to E. crasswn, from Avhicli it differs in the pro- 

 portionate lenpjth, being only twice instead of three times as long as broad ; in the 

 size being only three-fourths as large ; and especially in the peculiar lateral split- 

 ting, as it were, of the basal lobes. 



IS July, 1872. 



