IDENTIFICATION OF MARINE GROWTHS. 



13 



Key to Section B of Dby-Docking Report. 

 {See also key to Section A if required,) 

 (!) Organisms with a Shell. 



(h) Flat patches of a limy encrustation, honey- 

 comb in structure ..... 



(2) Organisms with no Shell. 

 (i) Branching types : 

 {i) Branches expanding from a single base or 

 forming a moss-like tangle ; never possess- 

 ing heads on the stalks and showing a 

 honeycomb structure under a good lens . 



(i) 



Green weeds : 



(1) Soft and flexible tubes, varying in 

 thickness from that of human hair to 

 about \ in. or more, usually little 

 branched ..... 



Single threads, with a slimy feeling, 

 of the thickness of a human hair 

 or much narrower, the individual cells 

 in the wider threads just recognis- 

 able under a good lens . 



Richly branched threads, forming tufts 

 1-2 in. long, with a rather harsh feel- 

 ing, the long component cells readily 

 seen with a lens .... 



Broad papery sheets . . 



(2) 



(3) 



(4) 



{k) 



Brown weeds : 



(1) Threads forming short tufts or long 

 hanging tresses, usually extensively 

 branched, but the majority of the 

 branches much narrower than those 

 ofCladophora. (N.B. — These growths 

 may appear green after a stay in 

 fresh water) . 



(2) Similar branching threads, with a more 

 slimy and softer feeling than those 

 of Ectocarpus; under a microscope 

 are seen to consist of mucilage tubes 

 harbouring boat -shaped diatoms 



Red weeds : 



(1) Branched threads, often repeatedly 

 forked, the two arms of the ultiriiate 

 forks often curved inwards like a pair 

 of tongs; threads with alternating 

 darker and lighter cross bands 

 Branched threads, in which the elon- 

 gated cells are arranged in successive 

 horizontal rows, especially obvious 

 ill the upper parts 



(ii) Soft-bodied forms : 

 (m) Jelly-like masses or transparent leathery bags 

 (n) Opaque bag-like or spongy structures . 



H) 



(2) 



POLYZOA. 



POLYZOA. 



Enteromorpha. 



Urospora. 



Cladophora. 

 Ulva. 



Ectocarpus. 



SCHIZONEMA. 



Ceramium. 



polysiphonia. 



Sea-Squirts, 

 Sponges. 



