Fresh-Water Algce of Canada. 463 



racters are that the cells containing the sporangia are not inflated, 

 and the sporangia are oval ; neither of which appearances have ' 

 we been able to observe or verify. 



Z. CATEN^EEORME. HaSS. 



" Char. — Filaments a little finer than those of Z. malformation 

 Cells usually rather more than twice as long as broad. Spo- 

 rangia largely inflating the cells in which they are contained, 

 acutely oval." Hass. 



Hass. Hist. F. W. Alg., p. 147, pi. 30, figs. 3 and 4. 



Hob. — Paris, C. W., in pools. 



This is the second species which has been found conjugated in 

 Canada to our knowledge. It was collected during the last 

 autumn, and had the appearance of age. We have represented it 

 in fig. 6 (p. 459) as it appeared in conjugation under an objectglass of 

 100 diameters. This species, Hassall informs us, cannot be dis- 

 tinguished from " Z. commune before conjugation. After this has 

 occurred, the difference in the length of the cells, and the form 

 of these is so obvious, as not to leave any doubt of its being dis- 

 tinct from that species." In Z. commune the sporangia do not, 

 it would appear, occasion any inflation of the cells in which they 

 are formed, whereas in this species the cells are considerably in- 

 flated, as may seem in the figure 6. It appears to us that this is a 

 very doubtful difference. It is very questionable whether such a 

 difference will uniformly characterise all the individuals of either 

 species. We suspect that there is no real difference between the 

 two, and that they are in fact one and the same plant. Berkeley 

 remarks that " Characters like those in HassalPs F. W. Algae, de- 

 pendent simply on comparative size, are altogether inadmissible." 

 Until, therefore, we can obtain some more thorough discrimina- 

 tion of the species belonging to this family; we must be satisfied 

 with such as we have. 



Besides these species named we have collected probably Z. rivu- 

 lare, Z. commune, and Z. gracile. We have frequently observed 

 several other — as we think — distinct species ; but, in the absence of 

 conjugation and sporangia, we have not been able to identify 

 them with any of those described by Hassall. We hope in a fu- 

 ture paper to enter more at large into the discrimination of the 

 species to be found in the waters of Canada. 



The species of this family are, with scarcely an exception, in- 



