STAURASTIUJM. 165 



SECTION D. 



Cells furnished with small granules, generally 

 covering the whole cell- wall, and regularly or irregu- 

 larly disposed. 



* Granules few and restricted to the angles which are produced 

 (submamillate). 



'27. St. trachytithophorum. 

 ** Granules more or less eveulv distributed all over the cells. 



i 



t Semicells pyramiclate- truncate. 



28. St. botrophilum. 

 ft Semicells elliptic with broadly rounded angles. 



J Sinus open. 29. St. turgescens. 



+ Sinus closed and linear : semicells elliptic -pyra- 

 midate. 



30. St. Donardense. 



ttt Semicells oblong-elliptic, angles more or less produced 

 and often subtruncate, apex flattened. 



31. St. alternans. 



32. St. dilatatum. 



33. St. disputatuni . 



34. St. striolatum. 



35. St. ruc/ulosum. 



t tft Semicells angularly elliptic (often rhomboid-elliptic), 



with a strongly convex apex. 



+ Angles rounded or broadly rounded, destitute of a 

 mucro. 



36. St. punctulatum. 



37. St. dispar. 



38. St. pilosellum. 



++ Angles slightly rounded, furnished with a mucro. 



39. St. gmnulosum. 



40. St. paxilliferum. 

 t^ttt Semicells angularly rotund (subcircular). 



41. St. inflatum. 



27. Staurastrum trachytithophorum W. & G. S. West. 



(PL CXXVI, figs. 1, 2.) 



Staurastrum trachytithophorum W. & G. S. West, Alg. S. England, 1897, 

 p. 493, t. 6, f. 22. 



Cells small, about as long as broad, deeply con- 

 stricted, sinus open and subrectangular, with an 

 acuminate extremity ; semicells very widely cuneate, 



