<;i«) 



from July 1899, must to my thinking be regarded 



as a new species, and Dr. O. Nord s led l ol' Lund 

 is also of the same opinion. 



The following is a shorl diagnosis: — 



St. mediocre, 2 — 2 1 /s plo latins quam longius 

 (cum processibus) , modice constrictum , incisura 

 parva mox ampliata; semicellalae triangulares, apice 

 concavo glabratoqtie, marginibus convexis, glabratis, 

 angulis in processibus longioribus, gracilioribus pro- 

 ductis, extrorsum sæpe leviter deorsum incurvatis, 

 spinis simplicibus (rarissime furcatis?), in series or- 

 dinatis, præditis, apicibus 4 furcatis; a verlice visæ 

 triradiatæ, medio glabro, processibus aculeis munitis. 



Long. cell — 2Sfi; lat. cell cum proc. = 68/*; 

 lal. isthm. — 11 fi. 



This species reminds one somewhat of St. acu- 

 leatum, but in the latter the spines are usually fur- 

 cate, and more evenly distributed over the whole 

 of the cell. It also bears some resemblance to 

 St. controversnm Bréb. and St anatinum C. el W., 

 bul is, however, quite distinct from both of them. 

 Dr. Nordstedt has cailed my attention to Sl.aspi- 

 nosum Wolle 1 which also comes near the present 

 species, but differs from it in some essential points. 

 Il may also be compared to St. limneticum Schmidle 

 var. rectum Lemm. 2 . 



Finally I may point out that whal I have 

 cailed St. paradoxum Meyen: »In Planklon from 

 Sorvaagsvatn« (1. c. p. 2'M) is undoubtedly this alga ; 

 it occurred very sparingly in the sample from 1897, 

 hence the reason why il was not closely investi- 

 galed at that time. 



11. Xanthidium quadricornutum Roy & Biss. 

 Formå longispina Borgs. Freshwater Algæ, p. 229, 

 plate VII, fig. 13. 



Fig. 1 19. Closterium 



aciculare West. '-■" ,. 



F. I!, del.) 



1 Wolle: Desmids ol' the United States, p. 14.'!. tal). ;>1 

 lig. 22. 



- Lem inerma n n, E.: Planktonalgen, Ergebnisse einer Reise 

 nach dem I'aeifie (Abh. Nat. Ver. Brem., Bd. XVI, 189!)) p. 344, pi. 1, ligs. 11 — 12 



