CROALL, MARINE ALGiE OP GREENLAND. 279 



23. Holosaccion ramentaceum, J. Ag. 



There arc numerous examples of this, many of them quite 

 simple, and others abundantly branched, and from 3 to 7 inches 

 in length. Jakobshavn, Sakkak (2 fathoms), &c., v.c. 



24. Rhodymenia palmata, L. Jakobshavn, in 3 fathoms, July. 



Cerameace^. 



25. Ceramiwn rubrum, J. Ag. 



A rather slender form, the main stems opaque, the branches 

 sub-diaphanous. It may prove a distinct species when this 

 puzzling genus is better understood. Washed up on the beach at 

 Godhavn. September. 



2Q. Ptilota serrata^ Kutz. 



Another intermediate form, and equally puzzling. Only a few 

 fragmentary specimens were observed, mixed with other species ; 

 the smallest of these, however, exhibit the doubtful character of 

 the species. Jakobshavn, 3 fathoms ; just below highwater- 

 mark at Claushavn, covered with Cellularia reptans. 



27. Callithamnion americanum^ Harv. 



Only a few fragments of what seems referable to this species ; 

 were detected among Rhodophyllis veprecula. It is remarkable 

 for the length of the joints, and the patent and attenuated 

 branches. 



28. C. Rothii, Lyngb. 



Scarcely differing even in luxuriance from well-grown specimens 

 on our own shores. 



CHLOROSPERME^. 



SlPHONACE^. 



29. Bryopsis plumosa, Ag. 



Specimens small, but characteristic of the species. The size 

 may depend partly upon the season (June), and partly on the 

 locality (in rock-pools). 



CONFERVACEiE. 



30. Cladophora arcta, Kutz. 



In the collection there are numerous specimens exhibiting the 

 plant both in the spring and summer form, some of them in a 

 beautifully sporiferous condition. Pools on shore, 'Jakobshavn, 

 June ; Egedesminde, sandy shore close to high-water mark, June 

 10; Sakkak, 2 fathoms, August. Godhavn, washed on beach, 

 September. 



31. Conferva arenosa, Carm. 



Agrees in structure, but the filaments finer than usual in this 

 species. Jakobshavn, rocks on shore. July. 



32. C, mclagonium^ Web. et Mohr. 



The specimens agree well in structure, but their luxuriance is 

 remarkable ; from 18 to 24 inches being the average size. They 



