SPHiEROCOCCOIDE^E. 137 



side of the midrib of the frond. Mrs. Griffiths main- 

 tained that this was constantly absent in all states of 

 her plant, while it was as constantly present in D. alata 

 proper. Professor Agardh appears either to have adopted 

 Mrs. Griffiths's view of the matter, or to have formed a 

 similar opinion, for he speaks of D. alata var. angus- 

 tissima, and D. angustissima : of the former as a variety, 

 of the latter as a distinct species, and adds, that the two 

 must not be confounded, for their characters are differ- 

 ent. 'Dr. Harvey, Dr. Dickie, and others, on the con- 

 trary, believe that the absence of the membrane is acci- 

 dental, and that the supposed D. angustissima is but an 

 extremely narrow form of D. alata. I have never seen 

 a growing plant of the reputed D. angustissima, but 

 I have carefully examined Mrs. Griffiths^ and Miss 

 Hutchins's specimens in the British Museum, and in 

 the private collection of Mrs. Gray, and I am bound to 

 confess that these do confirm Mrs. Griffiths's descrip- 

 tion. There is no membrane, and the appearance of 

 the plant is very different from the normal state of 

 D. alata. I am not prepared to decide whether these 

 be sufficient grounds to constitute a title to specific 

 rank; but I feel that they do justify me to maintain 

 a species which already exists in the works of Harvey 

 and Agardh. There can be no doubt that many speci- 

 mens which are called D. angustissima are only narrow 

 forms of D. alata; but it does not necessarily follow 

 that Mrs. Griffiths's plant is not a distinct species. 



Delesseria hypoglossum. The proliferous 

 Delesseria. 



Fronds growing in tufts from a minute disc-root, and 



