720 MINNESOTA BOTANICAL STUDIES. 



the pinnules in the upper portion are robust and fan-shaped, 

 generally crenulated at the external margin. 



Most common between tide marks on the margins of the pools. 



9. Corallina aculeata sp. nov. PL LV., Fig. 3; PL LVL, 



Figs. 18-19. 



Fronde 5-10 cm. alta, stipitata, irregulariter bi-tripinnata, 

 saepe pinnulis ex apice articuli egredientibus ; articulis inferiori- 

 bus diametro sesquilongioribus, pinnarum pinnularumque fragil- 

 issimis digitato-laciniatis aculeatio, ssepe cylindraceis vel line- 

 aribus ; conceptaculis subcompressis cornibus aculeatis. 



The pinnules of this plant are characteristic : they are brittle, 

 delicate and confusedly branched. The ultimate articuli of the 

 main branches as well as some of the young pinnules are al- 

 ways weakly calcified ; and the apices of these articuli are 

 liable to shrink in the exsiccation. In other respects it is 

 closely allied to Cor. vancouveriensis f. typt'ca^ so that it might 

 be taken as a local form caused by the mode of habit. Indeed 

 a young and sterile frond of this species is hardly separable from 

 it, if the apical articuli were not weakly calcified. 



Common; high-tide pools. 



EXPLANATION OF PLATES. 



The figures in Plates LI.-LV. are all in natural size, taken from 

 the alcoholic specimens. 



PLATE LI. 



1. Amphiroa cretacea Endl. var. tasmanica Sond. 



2. Amphiroa tuberculosa Endl. 



PLATE LII. 



1. Cheilosporum frondescens (Post, et Rupr. ) f. typica. 



2. do. f. intermedia. 



3. do. f. maxima. 



4. do. f. polymorpha. 



PLATE LIII. 



1. Cheilosporum planiusculum (Kiitz.) f. regularis. 



2. do. f. normalis. 



3. An abnormal form of the same species found at high-tide mark. 

 The fronds are filamentous with moniliform articuli; a few sagittate 

 articuli are to be found in some parts. 



