ridia ?) form very large, continuous, cloud-like patches, 2-4 inches long, 

 covering the whole lamina, at both sides of the midrib, often for half the 

 length of the lobe. The membrane is of a thickish, half-coriaceous substance, 

 not very readily tearing, and is everywhere dotted with muciferous spores. 

 The colour is a full olive or olivaceous-brown, pretty well preserved in dry- 

 ing ; in which state the frond imperfectly adheres to paper. 



In several respects this species resembles the European H. poly- 

 podioides, with which I formerly confounded the first imperfect 

 specimens sent from Australia, many years ago, by Mr. Gunn. 

 But it has a much more firmly membranous and almost cori- 

 aceous lamina, not often tearing into shreds, as is the habit of 

 the European ; and when in fructification the two cannot be 

 mistaken. It has been named in compliment to Dr. Mueller, 

 who first sent to Europe fiuiting specimens. The young plant 

 differs considerably in aspect from the mature, having shorter 

 and broader and much blunter laciniae, and being of a paler 

 colour. Specimens from tide-pools are often much stunted ; 

 those from deep water much taller, but sometimes very narrow. 



Fig. 1. Haliseris Muelleki, — tlie natural size. 2. A section through the 

 frond. 3. Part of the surface, with a portion of the sorus : — magnified. 



