













470 





SYSTEMATIC POSITION OF THE DICTIOTACE^J. 







and Special Morphology,' p- 67. The affinities of the Dictyotacea 

 to these Phceosporea may be thus roughly represented : 





Dictyotace^j. 











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TlLOPTERTDE^. 



Pylaiella fulvescens. 

 Pylaiella littoralis. 

















Ectocarpus secundus 

 ? Ectocarpus Zebelii. 



Ectocarpus siliculosus. 

















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Ectocarpus pusillus. 



The material on which my investigations have been made was 

 obtained by dredging, mainly off the Mewstone in Plymouth 

 Sound. 



I take this opportunity of acknowledging my indebtedness to 

 Mr. G. C. Bourne, late Director of the Marine Biological Labo- 

 ratory, Plymouth, for having placed at my service the steamboat 

 and other accessories for collecting-purposes. Having regard to 

 the requirements of the zoologists at the Laboratory, I could 

 scarcely have enjoyed greater facilities had they been entirely 

 under my own control. 













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EXPLANATION OF PLATE XIII. 



Transverse 



of male plant showing midrib and anthe- 

 n m'™ onfli^rli-urr, • /?' dehisced iwthe- 



ridia. X 120. m, midrib ; a, ripe antheridium ; a\ 

 ridia; t, involucre. 

 2. Transverse section of stalk showing secondary corfc 



X 



midrib of fig, 1 ; c, cambium cell ; sc.c, secondary cortex ; s f 

 by disappearance of lamina of thailus. 



120 



120. m, 

 scar left 



3. Longi 



4. A portion of male plant showing antheridia in position. X 3. "> tu 



of hairs. 



5. A portion of thailus showing an antheridium in surface-view 



X 



120. 



















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