156 ERYTHEA. 



and more prominent, until finally sucli a stage as the one 

 represented in figure 3 of Plate V, is reached. 



C. Development op Pinnules or Sporophylls. 



In the older stages of the young plants, we find that the 

 outgrowths at the base of the frond become even more and 

 more numerous and larger and larger as they recede from 

 the transition-place until finally we have well-developed 

 pinnules as represented in figure 4 of Plate V. The main 

 portion of the blade is the prominent feature of this form, 

 but the pinnules are conspicuous and show distinctly that 

 they belong to the blade rather than to the stipe. They may 

 be traced through the different stages from the larger flat- 

 tened ones above, to those just appearing as outgrowths at 

 the point of union of the stipe and blade (" transition-place"). 



As the older portions of the blade wear away above, the 

 developing pinnules grow to be larger and larger, until 

 finally such a form as that represented in figure 5 of Plate V 

 is produced, where the mature pinnules are each of them 

 fully as large as, or even larger than, the blade itself. 



It is in such a stage as the one just described that the 

 special characteristics of the genus Eisenia begin to be 

 developed. We notice that the lower margins of the blade 

 begin to turn in towards one surface. 



D. Development of the Arms. 



Up to the time when the lowermost margins of the blade 

 begin to become involute, the base of the blade and the 

 transition-place have presented perfectly plane surfaces and 

 have resembled very closely young plants of Ecklonia. This 

 resemblance is very striking and does not disappear until 

 the turning in of the margins begins to be decidedly pro- 

 nounced. Nothing of the sort occurs, as far as the writer 

 knows, in any species of Ecklonia. Certainly there is no trace 

 of it even in fairly large specimens of Australian Ecldonia 

 radiaia in the writer's possession. The scarcity of material, 

 however, and the absence of direct statements upon this 



