Spencer. — On the Fresh-water Alg® of Neiv Zealand. 297 



Pediastrum tetras, and P. heptactis are both common. 



,, pertusum. Intestines of the frond hyahne ; some of the inner 



cells are gone, therefore the foraminal appearance is uncertain. The 

 rectangularity of the outer row of cells and the shape of the notch point to 

 pertusum. On the other hand, the number of rows, and the number of 

 circumferential cells, might lead one to infer a new species. On careful 

 comparison, however, I am inclined to consider it as an unusually large 

 specimen of P. pertusum. Number of rows, five; number of cells in inner 

 circle, five. The two next rows are broken down. The fourth circle con- 

 tains apparently eighteen, and the outer one — the fifth — twenty-one cells. 

 Fig. 9. 



Pediastrum., sp.n. Frond square, divided into four equal lobes by a 

 crucial hyaline division. Lobes divided into segments by a deep narrow 

 notch, which extends from the four corners towards the centre of the frond, 

 the segments again partially subdivided by a broad shallow notch. Side 

 view, four cells placed end to end, the central ones about twice the size of 

 the terminal. Although at first sight so very unlike, there is a remarkable 

 similarity between this plant and P. tetras ; in fact, the only point of differ- 

 ence consists in the secondary segmentation of the lobes. Fig. 10. 



Scenedesmus quadricauda. I have placed before you a figure of this 

 Desmid, because it shows the unusual phenomenon of a broad well-defined 

 coating of hyaline matter external to the cells, and further that the bristles 

 are appendages of the investing coat and not of the cells themselves. 

 Fig. 11. 



DlATOMACE^. 



Meridian constrictum, H., xcvi. ; M.Dic, 12. 

 Diatoma elongatum, H., xciv. 



,, vulgare, H., xciv. ; M.Dic, 12. 



,, grande, M.Dic. 

 Melosira. 



Campylodiscus costatus, M.Dic, 12. 

 Surirella bifrons, M. Die, 13. 

 Synedra splendens, H., xcvii. 

 Cocconeis placentula. 

 Navicula. 

 Gyrosigma macrum, M.Dic, 11. 



„ attenuatum, M.Dic, 11. 



Pinnularia oblonga, M.Dic, 11. 

 Stauroneis phcenicenteron, M.Dic, 11. 

 Encyonema. 



SO 



