220 BRITISH DESMIDIEE. 



Closterium acuminatum, Kiitzing, Phycoloyia Germajiica, p. 130 (1845), 

 (according to Kiitzing in lit.). 



Falaise, Brebisson. Germany, Kiitzing. 



I am miable to distlngviish Closterium arcuatum from C. Diance ; but in 

 drawings sent me by M. de Bre'bisson, the latter has distinct terminal notches, 

 which are wanting in the former. 



27. C. Venus (Kiitz.). 



Closterium Venus, Kiitzing, Phycoloyia Germanica, p. 130 (1845) ; in lit. 

 cum icone. 



Germany, Kiitzing. 



I am indebted to Professor Kiitzing' s kindness for a drawing of this species, 

 but I must confess that I am unable to discover any characters sufficient to 

 distinguish it from Closterium Dianee. 



Tab. XXXV. fig. 12. Frond, from a drawing by Professor Kiitzing. 



28. C. Amblyonema (Ehr.) ; frond stout, linear, slightly curved, 

 twenty times longer than broad ; ends rounded. 



Closterium lineatum, Bailey, American Journ. of Science and Arts, v. 41. 



p. 303. t. l.f. 34 (1841).? 

 Closterium Amblyonema, Ehrenberg, Verbreitung und Einfluss des Mikrosk. 



Lebens in Siid- und Nord-Amerika (1843). 



West Point, New York, Bailey. 



29. C. uncinatum (Kiitz.) ; frond slender, finely and closely striated; 

 extremities tapering to a subacute point and suddenly curved 

 downwards. 



Closterium uncinatum, Kiitzing, Phycoloyia Germanica, p. 131 (1845) ; in 

 lit. cum icone. 

 Germany, Kiitzing. 



30. C. decussatum (Kiitz.) ; frond stout, finely and closely striated, 

 slightly curved, gradually tapering ; extremities slender, but obtuse 

 at the apex. 



Closterium decussatum, Kiitzing, Phycoloyia Germanica, p. 131 (1845) ; in 

 lit. cum icone. 

 Germany, Kiitzing. 



A drawing sent me by Professor Kutzing represents the strise as regularly 

 crossing each other, so as to form diamond-shaped reticulations. As this 

 appearance is not unusual in dried specimens, when the flattened frond permits 

 the strife of both surfaces to be visible together, I will venture to suggest the 

 possibility that Professor Kiitzing's drawing may have been taken from a 

 frond in that condition. Closterium decussatum seems (o differ from C. tur- 

 gidvAU ill its more tapering extremities. 



