THE ELK-KELP. 183 



and loosely ruffled. The margins are generally provided with 

 more or less remote spine-like projections, which, also, may 

 occur sparingly upon the surfaces of the blade. In one 

 specimen obtained, these spine-like projections were entirely 

 wanting. The surfaces of the blades are coarsely and trans- 

 versely rugose, as is represented very well in the accompany- 

 ing figure. 



The most noticeable features of the leaves are their length, 

 their cuneate bases, and the fact that they are bilaterally 

 symmetrical. Areschoug says that the leaves, in the single 

 specimen which he possessed, were 5.6 meters long, much as 

 in the specimens obtained by the writer. Cleveland's speci- 

 men, described in Farlow's paper, is said to have leaves 

 " 3 to 4 inches broad, and from 2 feet and upwards in length." 



The method by which the leaves originate, is unknown. 

 In N. Luetkeana, there is at first a single blade. This di- 

 vides into two, and each of these divides again, making four 

 blades. These four blades form the centers of activity 

 during the rest of the division. Equal divisions and sub- 

 divisions take place in them and their derivatives with a fair 

 amount of uniformity, the blades developing and thickening 

 short petioles, which branch until finally there exist 4 sets of 

 petioles, branched dichotomously in turn, four to five 

 times, and bearing narrow blades, in all about 64. The 

 blades in all the specimens of N. gigantea examined by the 

 writer, numbered six to each arm, one upon the tip of each 

 petiole. Areschoug's specimen had four blades upon each 

 petiole. The number of blades is not given for Cleveland's 

 specimen, but he speaks of the petioles (" branches ") as fork- 

 ing once in each case, whereas, in the specimens both of 

 Areschoug and of the writer, the petioles are simple. 



This forking certainly points towards the origin of these 

 blades from one original blade, by successive, longitudinal 

 splittings, such as are characteristic of the Lessoniidese. The 

 origin of the blades in N. Luetkeana, is by successive, equal, 

 longitudinal splittings, and this species is consequently 

 referred without question to the subtribe Lessonie£e. The 



