042 W. A. Setchell — Classification and GeograpJiical 



tissues just under that surface, the other surface is not at all fur- 

 rowed but perfectly plane. Consequently the blade of Costaria is 

 not really plicate but ribbed, and each particular rib is confined to 

 one surface, there being three on one surface and two on the other. 

 Besides the ribs, the blades of the older specimens possess bullate 

 swellings and these swellings are sometimes perforated as in Agarinn. 

 This is the rule in the var. pertitsa^ Harv/ 



Cymathcere, J. Ag. — This genus was established by J. Agardh to 

 receive the Laminaria triplicata, P.&R. The holdfast is dis- 

 coidal and in this it resembles L. soUdungida, J. Ag. The stipe is 

 short. The blade possesses three longitudinal "plicae" according to 

 J. Agardh'^ and five according to Areschoug.^ These "plicae" are 

 crowded together in the central portion of the blade w^hich is also 

 thickened in this region. J. Agardh also says:^ that the blade is 

 " inferne involuta " in the young fronds. The writer has had the 

 opportunity of examining a Postels and Ruprecht specimen collected 

 by the Liitke expedition and preserved in the herbarium of Prof. 

 Farlow at Cambridge, Mass. It is a rather young specimen and 

 shows the discoidal base and the blade with the thickened central 

 portion. The longitudinal " plicae " are not very distinct, and the 

 transition-place seemed to be plane and not provided with scroll-like 

 structures. 



Arthrothammis, Rupr. — The species of this genus belong in the 

 northern Pacific and are ver}^ little known. Ruprecht has figured 

 the type^ A. Kurilensis and a figure of A. hifidits, J. Ag. {A. 

 radicans, Rupr.) is represented in plate 15 of Postels and Ruprecht's 

 " Illustrationes Algarum." A. longipes^ J. Ag., and A. Bongar- 

 diana (P.&R.), J. Ag. are probably incorrectly referred to this 

 genus. The blade in both A. Kurilensis and A. hifidus seems to be 

 plane but at the base it unrolls, in each species, from two small 

 scrolls similar to those in Agarum Titrneri. The stipe of A. Kuri- 

 lensis is forked^ and marked with a spirally twisted scar after the 

 fashion of Thalassiopliyllwn. The stipe in ^4. hifidus is said to be 

 decumbent'^ and repeatedly bifurcate, emitting ''roots." A specimen 

 of Laminaria bifida^ P.&R., collected by the Liitke expedition, in 

 Prof. Farlow's herbarium shows a long undivided blade involute 



1 Proc. Am. Acad., vol. iv, p. 329, 1859. 



2 De Laminarieis, p. B. '•'• Obs. Phyc, Ft. 4, p. 20, 



4 Loc. cit, p. 3. -^ Mem. Imp. Acad. St. Petersb., t. 6, PI. IT, 1848. 



^ Cf. Ruprecht's figure, loc. cit. '' Cf. Areschoug, Obs. Phyc, Pt. 5, p. 14. 



