89 



DESCKIPTIOX OF THE PLATES. 



Plate I. : The General Habit. 

 Fig. 1. A typical form of low- water mark. 

 Fig. 2. IS^arrow form, low-water mark. 

 Fiff. •). Bi-oad form, low-water mark. 

 Fiff. 4 ami 5. firoad forms, liigk-water mark. 



All these specimens, drawn natural size, 

 were collected in Port Erin liay, between the 

 Kith and 19th of May, 1901. 



Plate II.: Axatomy of the Shoot. 

 Fig. (i. Longitudinal section of frond apex, mounted in 



glycerine JpH}'- x ■>90. 

 Fio-. 7. Longitudinal section of a young' frond a short 



distance from apex, mounted in glycerine jelly. 



X 190. 

 Fig. S. Longitudinal section of older part of frond, 



examined in fresh sea water. x .')90. 



Plate III. : Anatomy of the Root. 



Fig. 9. Perpendicular section through the root and the 

 insertion of two upright shoots. The central 

 tissue of the latter is seen to end in the attach- 

 ment organ in a conical form. The root has 

 attached itself to the rock by aneliorlike out- 

 growtlis. X 54. 



Fig. 10. Perpendicular section through the upper layers 

 of the attachment organ mounted in glycerine 

 jelly. Xotice the regular and unbrauched cell 

 rows, and the series of caps which have been cut 

 off b}^ the tip of each ]'ow towards the surface. 

 X 1075. 



