BRITISH DESMIDIACE.E. 



Genus 18. STAURASTRUM (continued). 



SECTION E. 



Cells furnished with spines at the angles only, each angle pro- 

 vided with single or binate spines, rarely with three or four. 

 * Cells having a single spine at each angle. 



| Cell- wall smooth or minutely punctulate, never granulate 

 or verrucose. 



42. St. glabrum. 



43. St. Dickiei. 



44. St. apiculatum. 



45. St. dejectum. 



46. St. mucronatum. 



47. St. O'Mearii. 



48. St. pterosporum. 



49. St. connatum. 



50. St. jaculiferum. 



51. St. curvatum. 



52. St. megacanthuni 



53. St. aristiferum. 



54. St. cuspidatum. 



55. St. pseudocuspidatum. 



56. St. leptodermum. 

 |f Cell-wall granulate or even verrucose. 



57. St. Ungeri. 



58. St. tunguscanum. 



59. St. lunatum. 



60. St. cornutum. 



61. St. Gatniense. 

 ** Cells with more than one spine at each angle. 



| Cell- wall smooth or punctulate, never granulate. 



62. St. bifidum. 



63. St. longispinum. 



64. St. Brasiliense. 



65. St. quadrangulare. 



66. St. quadrispinatum. 



VOL. V. 1 



