Distribution of the Laminariacece, 347 



feet) rather stout, flattened stipe which bears towards the top a 

 bunch of leaves. Younger specimens show the arrangement of these 

 leaves better than older ones. At the top there is a long strap- 

 shaped blade tapering gradually to the base and with the central 

 portion thickened into a sort of indefinite midrib. Below this are 

 two ranks of leaves along the stipe arranged with their blades in 

 the same plane with the terminal blade. These leaves are the 

 sporophylls and are much the same shape as the terminal blade 

 but lack the midrib. They are eroded at the tip and appear to 

 increase in length at their own transition-places. It may be seen 

 from younger specimens that the sporophylls arise as outgrowths 

 from the lower portion of the transition-place. Below these sporo- 

 ph3''lls are scars on the stipe where older sporophylls have been 

 situated. Neither the terminal blade nor the sporophylls ever pos- 

 sess cryptostomata. 



Alaria^ Grev. — The genus Alaria contains between 15 and 20 

 species which are at present both little known and in a state of con- 

 siderable confusion. They agree very well in their general charac- 

 ters, the species being founded on details which are likely to vary 

 considerably in individuals of the same species. 



The terminal blade in Alaria is much elongated and possesses a 

 very distinct midrib. It is also provided with abundant cryptosto- 

 mata even in adult specimens. The sporophylls are in two ranks 

 on the upper portion of the stipe and arise as outgrowths from the 

 lower part of the transition-place. The sporophylls in Alaria seem 

 to be of definite growth, i. e. they grow to be of a certain definite 

 size and then stop. Their distal ends are rounded and never eroded 

 as in Pterygophora. They are destitute of cryptostomata except 

 in rare and apparently abnormal specimens. Afi;er maturing the 

 zoosporangia the sporophylls drop off and their oflice is performed 

 by younger ones. 



Alaria differs from Pterygophora in possessing a more definite 

 midrib and cryptostomata in the terminal blade and by the definite 

 growth of the sporophylls. 



Subtribe 2. Eeklonieae. — This subtribe contains three curious- 

 and little known genera, viz : Ulopteryx, Ecldonia^ and Eisenia. 

 They all possess pinnatifid fronds and the pinnae, on examination, 

 are found to be sporophylls which arise at the base of the blade 

 rather than at the tip of the stipe» This forms the distinctive fea- 

 ture of the subtribe. 



