47 



longum qnam latum, medio profunde constrictum, sinu acutan- 

 gulo ampliato ; semi-cellulis a fronte visis ellipticis divergenti- 

 bus, quasi obverse lunatis, granulis in series transversas ordina- 

 tis ; angulis productis bifidis achrois ; dorso papilloso angustato 

 producto, et late truncato ; semi-cellulis a vertice visis triangu- 

 laribus; angulis rotundatisbrevi mucrone imposito ; lateribus aut 

 rectis, aut leviter concavis, in medio papillis ornatis, nonnunquam 

 productis bifidis. Diam. .0013"-. 0015''. 



The nearest approach to this plant is a form found in Nor- 

 way, and described by Mr, Nordstedt under the name of .5*/. 

 arcuatum. The papillae are sometimes distinctly seen arranged 

 in a circle of which 4-6 present themselves as marginate ; these 

 are sometimes elongated and bifid. 



St. comptum^ n, sp. S. parvum, granulatum, sinu amplissi- 

 mo ; semi-cellulis subfusiformibus, dorso convexis, isthmo cyl- 

 indrico plus minus elongato conjunctis, a vertice 6 radiatis ; 

 radiis strictis, apice subtricuspidatis. Diam. lat, 00116" ; long. 

 0015". 



St. pusiHum^ n. sp. S. perexiguum, oblongum, rectilineare ; 



sinu iridistincto ; angulis in cornua divergentia productis; a 



vertice quadrangulare ; angulis radiatim productis. Diam. Lit. 



.0003'' ; long. .00055" > ^*"^"^ cornu duplo longiore. 

 Xanthidium, Ehrb. X. Antllopaeum, Breb. z^ar. triquetrum, Nordst. 



Similar to a form found in Brazil. — X. Arctiscon, Ehrb.=Staur- 



astrum Arctiscon, Lund.=St. munitum, Wood. 

 Arthrodesmus, Ehrb.— ^. fragiUs, 71. sp. A. sublaevis medi- 



ocris, profunde constrictus ; aculeis subulatis strictis ; semi-eel- 



lulis subsphaericis, vel late ovalibus (lat. 0015/' long, 0013") 

 utroque fine aculeo longo recto instructis ; aculeis plerumque 

 deciduis. Diam. cum aculeis ad •0045'''. Hab. in stagnis prope 

 Hammonton, New Jersey; Aug. 1879. / 



ZYGNEMACEAE. 

 Spirogyra, Link. — S. stagnalis, Hilse. — S. intermedia, Rabh. 



Zygogonium, Ktz^— Z. pectinatum, Ktz. 

 Zygnema, Ktz.— Z. leiospermum, de By. 



PleurocarpuS, A. Br. — F. tenuis, 7t. sp. P. cellulis diametro (0008"- 

 001'') plerumque equalibus, rarius duplo longioribus, obscuro- 

 viridibus vel atro-purpureis^ sterilibus. Hab. in lacubus, New 

 Jersey, 



I sent this plant out when first discovered as a Zygnema. 

 Later collections prove it to be a distinct species as named. 



Vaucheria, DC. — V, racemosa, Walz. Fine specimens. Coll. by 



Dr. Hobby, Iowa City- 



Conferva, Link. — C. tenerrima, Ktz. — C. abbreviata, Rabenh. 



Rhizoclonium, Ktz. — R. fluitans, Ktz. Frequent in streams in N, J. 



R. flavicans, Jiirg.— R. Casparyi, Harv. 



Oedogonium, Link. — O. flavescens, Hass. Atsion, N* J.— O. decipi- 

 ens, Wittr. and O. crassum, Wittr. Coll. by Dr. Hobby, Ktz., Iowa 

 City.— O. cryptoporum, Wittn, frequent -O.stagnale, Wittr., from 

 Bound Brook, N. J.— O. fragile. Wittr. Coll. Dr. Beardslee, Ohio, 

 and J. D. Smith, Florida.— O. polymorphum, Wittr. & Lund, 



