162 MINNESOTA BOTANICAL STUDIES. 



6). The basal portion remains somewhat thicker than the rest, 

 and at its end narrows into a short stalk {Jig. 12). As the stipe 

 grows from its upper end, more and more gonidiophylls are 

 produced laterally by the activity of the meristem, so that finally 

 from thirty to fifty, with the youngest nearest the base of the lam- 

 ina, may be present. The stipe, which normally is terete in 

 form, becomes somewhat compressed in the area where the 

 gonidiophylls are situated, but its anatomical characters do not 

 change. The sori cover both surfaces of the gonidiophyll. The 

 paraphyses, found among the gonidangia are much larger than 

 these {Jig. 30). The gonidangia are club-shaped with a thick 

 base ; the paraphyses, on the other hand, are very thin and del- 

 icate at their bases but as they reach above the gonidangia they 

 thicken out into a club-shaped upper end which has a large 

 cuticular cap on its upper surface, as in the case of Plerygo- 

 pho7-a. This cap is lamellate in character. Probably the pres- 

 ence of the paraphyses is a great protection to the gonidangia, 

 both in preventing their being preyed on, and in the gonidia 

 being set free before ripe, by the action of the surf. Mature 

 gonidangia measured from 70 mic. to 100 mic. in length, para- 

 physes from 150 mic. to 180 mic. in length. The cuticular cap 

 of the paraphyses measured in width from 26 mic. to 33 mic. 

 at the top, and from 14 mic. to 17 mic. thick. 



Description of Species. 

 Alaria nana sp. now 



Plant rather small, thirty to fifty centimeters long, green to 

 greenish brown in color; stipe rather long (4.5-7 cm. long), 

 firm, elastic, robust, terete ; rachis rather long (2-4 cm.), slightly 

 compressed, passing into the midrib gradually at upper end ; 

 blade about one sixth as wide as long (6.5-8.5 cm. in widest 

 part), rather thin, elastic, tapering slightly at upper end, mid- 

 rib prominent, .40-. 75 cm. wide, projecting equally on both 

 surfaces, somewhat rectangular in cross-section ; gonidiophylls 

 long, narrow, elliptical (6-12 cm. long, .75-1.50 cm. wide), 

 narrowed and thickened at base into a short stalk ; rachis bears 

 25-50 gonidiophylls as lateral outgrowths ; fruiting area cover- 

 ing both entire surfaces. 



Abundant in very exposed situations, covered only at high 

 tide, but always beaten about by the surf. 



