PLATE XVII. 



A. GRATELOUPIA, page 137. 



Fig. 1, G. filicina ; the natural size. 2, branch with 

 tetraspores. 3, longitudinal section of the same. 

 4, a tetraspore. 5, branchlet with favellidia. 6, 

 transverse section of the same ; magnified. 



B. GELIDIUM, page 137. 



Fig. 1, G. corneum. 2, the same, var. latifolium ; 

 both the natural size. 3, a ramulus with tetraspores. 

 4, tetraspores (dispores). 5, a favellidium imbedded 

 in a swollen ramulus. 6, spores ; all magnified. 



C. GIGARTINA, page 139. 



Fig. 1, G. acicularis ; the natural size. 2, branchlet 

 with fruit. 3, vertical section of a fruit. 4, longitu- 

 dinal slice of the frond ; all magnified. 



D. CHONDRUS, page 141. 



Fig. 1, C. crispus ; the natural size. 2, cross section 

 of an imbedded sorus. 3, a tetraspore. 4, longitu- 

 dinal slice of the frond ; magnified. 



