148 THE AMEEICAN MONTHLY [July, 



Fig. 27. — Staurastrum denticulatuni Arch. 



Fig. 28. — Staurastrum dubium nov. sp. (S. submagnum, latius 

 quam longum, scabro-granulatum, semicellulis fusiformibus, constric- 

 tione, profunda, radiis productis tricuspidatis et inflexis, a vertice tri- 

 angulare, ad basem semicellulse cum annulo singulo granulorum.) 



This species is nearly twice as broad as long, deeply constricted with 

 rough granules, processes inflexed, granulate and tricuspidate, semi- 

 cells somewhat fusiform, base annularly granulate, vertical view trian- 

 gular. 



This will no doubt prove a controversial species ; it is near S. man- 

 feldtiiV>€i'^.^ but smaller and with thicker processes; it is also more 

 regularly granidate. 



It also comes near S. fseudosebaldi Wille, but lacks the basal infla- 

 tion and the bifurcate spines. 



Fig. 29. — Docidium. The species has not been determined satis- 

 factorily. 



Fig. 30. — Cosmarlum ccelatum Ralfs, var. hexagonum nov. var. ( Var. 

 cellulis hexagonis, apicibus truncatis tetracrenatis, granulis centralibus 

 in seriebus linearibus ordinatis.) 



This differs from the semiorbicular type in having a distinctly hex- 

 agonal form, bearing four of the crenatures of each semicell at the 

 truncate ends ; the central granules are also arranged in linear series not 

 concentric. 



Fig. 31. — Cosmarlum controversum nov. sp. (C. medium, granu- 

 latum, dimidian partem circa longius quam latum, sinu anguste lineari, 

 semicellulis truncato-pyramidatis, granulis concentrice ordinatis, a ver- 

 tice subtruncato-ellipticis elevatione centrali lata, a latere obtuso-ovatis. ) 



Frond granulate, about one-half longer than broad, sinus deep and 

 linea, semicells truncately pyramidal, end view elliptic with a broad 

 elevation at each side, side view obtusely ovate, granules arranged 

 somewhat concentricallv. 



Fig. 32. — Staurastrum margaritaceum. Meneg. A form from 

 Capel Curig which shows short spines irregularly disposed at the apices. 



Fig. 33. — Euastrutn crass7i?n Ktz. A form of this species was fre- 

 quent which had a marked protuberance about half way up the side ot 

 the front view of each semicell. 



Fig. 34. — Micrasterias je7ineri Ralfs. var. simplex nov. var. (Var. 

 lobis quinque semicellulas leviter concavis et incisuris brevioribus.) 



This chiefly diflers from the type by having each of the five lobes of 

 the semicell but slightly concave, and the incision not so deep. 



Fig. 35. — Staurastrum proboscldeum var. subglabrum nov. var. 

 (Var. margine undiilato nee spinis truncatis vestitis, radii apicibus in- 

 tegris.) 



This diflers from the type in being undulately rough and not adorned 

 with truncate spines, as well as in the entire apices of the processes. 



Fig. 36. — See description of Fig. 5. 



Fig. 37. — Staurastrufn cumbrlcum var. ca7nbrlcu??z nov. var., forma 

 minor. 



It differs from St. Prlngshelmll Reinsch in its larger size, and in its 

 relatively sharper spines of varying lengths. It differs from St. sentl- 

 cosum Delponte in being longer than broad, whereas the latter is broader 

 than long, and also has its long spines more uniformly arranged. St. 



