CHONDRUS. 467 



DESCRIPTION OF THE PLATES. 



Plats I. : The General Habit. 



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

 Fig. 2. Narrow form, low-water mark. 

 Fig. 3. Broad form, low-water mark. 

 Fig. 4 and 5. Broad forms, liigli-water mark. 



All these specimens, drawn natural size, 



were collected in Port Erin Bay, between tlie 



16th and 19th of May, 1901. 



Plate II. : Anatomy of the Shoot. 



Fig. 6. Longitudinal section of frond apex, mounted in 



glycerine jelly, x 390. 

 Fig. 7. Longitudinal section of a young frond a short 



distance from apex, mounted in glycerine jelly. 



x 190. 

 Fig. 8. Longitudinal section of older part of frond, 



examined in fresh sea water. x 390. 



Plate III. : Anatomy oe 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 anchorlike out- 

 growths, x 54. 



Fig. 10. Perpendicular section through the upper layers 

 of the attachment organ mounted in glycerine 

 jelly. Notice the regular and unbrauched cell 

 rows, and the series of caps which have been cut 

 off by the tip of each row towards the surface, 

 x 1075, 



