258 MESSRS. W. WEST AND G. S. WEST OX 



A form of this was noticed which appeared to connect this species with S. quadran- 

 gulare, Breb., var. armatum, n. var. Perhaps these all belong to one species. 



117. Staurastrum quadrispinatum, W. B. Turn, in Naturalist (Eeb. 1886), p. 35, pi. 1. 

 tig. 4. (PI. XYIII. fig. 17.) 



Long. s. spin. 30-31 /t, c. spin. 43-49 ^i ; lat. s. spin. 29-30*5 ju, c. spin. 38-5-46 fx ; lat. 

 isthm. lO'S /I. 



The examples seen of this species were more strictly angular in both front and vertical 

 view s than Turner's figure. The spines in the vertical view were perpendicular to the 

 sides and almost in a line with the broadly truncate angles. The specimens had a 

 punctate membrane. Mr. L. N. Johnson has very recently recorded this species from 

 Indiana (in Bull. Torr. Bot. Club, xxi. (1894) p. 289). 



118. S- TRiPiDUM, Nordst. in Vidensk. Meddel. 1869 (1870) p. 226, t. 4. fig. 51. Forma. 

 (PI. XVI. figs. 20, 21). 



Long. 30-32 n ; lat. s. spin. 32-36'5 fi; lat. cum spin. 44-50 ^ ; lat. isthra. 10-12 ^. 



Var. iNFLEXUM, nov. var. (PI. XVI. fig. 22.) Var. semicellulis latioribus, sinu 

 extremum versus angustiori, apicibus subrectis, spinis longioribus valde inflexis et 

 leviter recurvatis ; membrana glabra. 

 Long. 285 /i; lat. s. spin. 305 ^, c. spin. circ. 44 /i; lat. isthm. 9 yw. 

 This agrees with var. glabrum, Lagerh. (in Ofvers. Sv. Vet.-Akad. Porh. (1885) n. 7, 

 p. 247), in the smooth membrane and longer spines ; but as his variety is not described 

 with inflexed spines, the forma torta placed by Bcergesen (in Vidensk. Meddel. 1890 

 (1891), p. 49, t. 5. fig. 56) under this variety should Idc var. injlexum, forma torta. 



119. S. spiCATUM, West & G. S. West, in Journ. Bot. xxxiii. (1895) p. 70. {_ = S. du- 

 biuni, B. Eichl. & Gutw. Nonn. Spec. Alg. Nov. 1894, p. 15, t. 5. figs. 52, 53 (non 

 >S; dllbilml,^\G^i, in Journ. Roy. Micr. Soc. (1890) p. 295, t. 6. fig. 28).] (PL XVI. 

 fig. 23.) 



The following is the description of the American specimens, w^ritten some time before 

 Eichler and Gutwinski's paper appeared : — 



S. parvum, tarn longuni quam latum (sine spinis), profunde constrictum, sinu aperto ct 

 acutangulo; semicellulse late suboblongae, lateribus et apicibus leviter concavis, 

 anguhs inferioribus spina brevi singula convergente instructis, angulis superioribus 

 spmis longis suberectis duobus instructis; a vertice visie triani>:ulares, lateribus 

 levissime retusis, angulis subrotundatis spina brevi singula et angulos versus 

 utrobique spina singula instructis ; membrana glabra. 

 Long. s. spin. 21 ^, c. spin. 385 n ; lat. s. spur. 21 ^u, c. spin. 29 /« ; lat. isthm. 75 /u. 

 This species is nearest to *!>'. qimndr angular e, Breb., var. longispina, BcErg. in Vidensk. 

 Meddel. 1890 (1891), p. 40, t. 5. tig. 55. 



120. 8. SUBTRIFURCATUM, nov. sp. (PI. XVI. fig. 24.) S. mediocre, sexta parte latius 

 quam longius, modice constrictum, sinu aperto acutangulo lateribus concavis; 

 semiceiluiai obiougae, lateribus valde concavis, apicibus leviter convexis, angulis 



