A Monograph of the Genus Alaria. 27 



between the successive two ; so also in A. prcelonga Kjellm. and 

 A. crassifoHa Kjellm. In A. cwcjusta Kjellm., the sporophylls are 

 condensed to a short, limited length of the stipe, and the inser- 

 tions of the petioles are fused together to form a narrow wing- 

 like portion on either margin of the stipe. A. nana Sche. is un- 

 rivalled among the genus in having the sporophylls ascending. A. 

 Pylaii Geev. is well known by having them at wide intervals on 

 a long stipe. All other species may belong to one of these ex- 

 amples, or may have a certain peculiarity in the disposition of the 

 sporophylls. 



Soldfasf, 



In the early embryonal stage of the frond, the holdfast of 

 Alaria is a simple scuteilate body firmly attached to the sub- 

 stratum with its under surface. It is better to call it hapter at such 

 stage. From all sides of the stipe just above the hapter arise 

 rhizines in an irregular whorl, furcating repeatedly towards the 

 periphery, each ramulet terminating in a small hapter. New 

 rhizines come out from the stipe above the older whorl as the 

 frond develops. The thickness and complicacy of the rhizines in- 

 crease in the new" ones. The primary hapter and the early-formed 

 rhizines decay by degi-ees. In these respects the mode of forma- 

 tion of the holdfast of Alaria agrees with wdiat has been hitherto 

 observed on various other genera of Laminariaceae. 



The rhizines of the holdfast are generally cylindrical in every 

 segment. In A. tceniata Kjellm. and A. angusta Kjellm., how- 

 ever, the principal segments, i. e., the segments directly connected 

 with the stipe, are stout and compressed and rhizines are very 

 few in number and short in length (Plate XV, fig. 1). The hold- 

 fast of A. fislulosa is built up of innumerable, long, filiform rhizines, 



