170 



a gentleman who has had considerable experience in delineating ob- 

 jects of this class, having executed for his own portfolio many faith- 

 ful representations of Algce and Diatomacea. 



EXPLANATION OF PLATE XXII. 



Fig. 1 . Zygnema quadratum. — a, sporangium in the vesicular state ; b c, sporangia 

 in the stellate form, all within the original cells ; d, e, /, g, stellate sporangia, in 

 the two latter some of the spines are bifurcated. 



Fig. 2. Zygnema varians. — a, a, sporangia in the vesicular state ; b, b, stellate spo- 

 rangia in the original cells, which are now much inflated. 



Fig. 3. Sporangium presumed to belong to a species of Tyndaridea, having been 

 found mixed with filaments of that Alga. 



Fig. 4. Lyngbya floccosa. — a, Sporangia within the frond ; b, sporangia before the 

 formation of the spines; c, with spines at an early stage; d, with spines fully 

 developed ; e, same as the last, but more highly magnified. 



END OK VOL. III. 



K. NEWMAN, PRINTER, 9, DEVONSHIRE ST., BIMIOPSOATE. 



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