l8 CALIFORNIA ACADEMY OF SCIENCES. [Proc. 3D Ser. 



The creeping, much branched, claw-like, prostrate frond 

 possessed by N. latissimmn is an excellent adaptation for 

 the purpose of enabling the plant to retain its foothold upon 

 the rough and seamy piles and rock surfaces which are its 

 habitat. Very little variation has been observed in the 

 prostrate frond ; and it seems to be a well defined and spec- 

 ially differentiated structure. 



Tetrasporic plants are of the most common occurrence. 

 Sporangia are produced very abundantly over the entire 

 surface, between the nerves and veins, thus adding to the 

 distinctive areolate aspect of the plant. The sori are minute 

 and crowded together, giving the impression of large sori 

 completely filling the areoles. Antheridial specimens have 

 been observed in but one locality. They reach a large size, 

 being among the most magnificent examples of the species. 

 In the early stages of development the antheridia form pale, 

 whitish patches. Later, they become more evident, and 

 when well developed, cause the entire frond to appear dull 

 reddish white. The surface of the frond is then decidedly 

 rugose. 



A comparison of JV. latissimwn with a specimen of N. 

 hillicB Grev., distributed by Le Jolis in Algues Marines de 

 Cherbourg, No. 215 (in herbarium W. A. Setchell), shows 

 a striking similarity between the two species in texture, 

 venation, and character of lobes or branches. A series of 

 specimens of N. hillice in the herbarium of Professor W. G. 

 Farlow shows that this plant varies greatly as to prominence 

 of veins. Careful comparison of N. latissimum with strongly 

 veined specimens of N. hillicB brings out a strong resem- 

 blance between the two. With the material in hand, how- 

 ever, it is not advisable to do more than point out the possi- 

 bility that the two species may be identical. 



It is desirable to call attention at this point to the latest 

 views of Agardh (1876, pp. 464 and 699, 1898, pp. 83-85) 

 concerning N. latissimum. 



According to Agardh, N. latissimum is a form which was 

 first collected by David Lyall at Vancouver Island, B. C, 

 and described by Harvey (1862, p. 170) under the name 



