34 University of California Puhlications in Botany [Vol. lo 



Fucus membranaceus f. obtusus f . nov. 



Plate 29 



Frons gracilis, plus minus caulescens, membranaeea, 30-40 cm. alta, 

 dichotoma, olivaceo-viridis vel" castanea, siccata obscure brunnea ; seg- 

 mentis strictis, linearibus val parum euneatis, comparative longis. 

 10-16 mm. latis, costa percursa, alis tenuibus, cryptostomatibus et 

 caecostomatibus numero paene aequalibus, 30-40 in quoquo cm. (piad- 

 rato, parvis, siccatis papillosis; receptaculis definitis, multo intlatis, 

 plerumque singularibus, partim bifidis, 2.5-4 cm. longis, 1-1.5 cm. 

 latis, truncatis, luteolis; conceptaculis plus minus numerosis, com- 

 parative parvis, non protrudentibus. 



Growing on rocks in the middle and lower littoral belts. Sitka. 

 Alaska. 



Type, Gardner, no. 2221 (Herb. Univ. Calif., no. 201155). June, 

 1910. 



This form has characters linking together forma acuminatus and 

 forma typicus of this species. It has the arborescent habit common to 

 both forms, the width of the fronds is intermediate, and the receptacles 

 are mostly simple and blunt, like neither form. 



Fucus membranaceus f. typicus f. nov. 



Plates 30 and 31 



Frons caulescens, 28-40 cm. alta, flaccida. membranaeea, dichotoma, 

 alis inferne attritis, costam comparative parvam, crassam cylindratam 

 relinquentibus luteolis; segmentis anguste euneatis vel linearibus, 

 10-18 mm. latis, puncto crescente in deprcvssione parva lunata dis- 

 posito, costa parum exposita, alis tenuibus, cryptostomatibus parvis, 

 20-25 in quoquo cm. quadrato, siccatis evidentibus, plerumque ad seg- 

 menta terminalia et subterminalia dispositis, receptaculis comparative 

 amplis, distincte definitis, plerumque inflatis, bifidis, apicibus longe 

 acuminatis; conceptaculis parum numerosis, comparative parvis, ob 

 colorem castaneum conspicuis. 



Growing on rock ledges and boulders in the middle of the littornl 

 belt. Sitka, Alaska. 



Type, Gardner, no. 3996 (Herb. Univ. Calif., no. 201213), July. 

 1917. 



I have taken this form to be the typical form of the species major, 

 more or less arbitrarily, it is true, but largely because it is a medium 

 among the known members of the group. I know of no way that one 

 could tell that it has given rise to all or to any of the other forms, oi- 

 that any one of the other forms has given rise to it. in fact whence 

 any of the forms came. The form was sparsely interspersed in groups 

 among the multiplicity of forms growing in tlie vicinity of Sitka. Tt 



