THE MARINE ALG.E OF NEW ENGLAND. 97 



1 ho plant is p»rcnni:il anil yonn:^ spocimon"* are entirely without porforations until 

 Ihey have attained a length of two or tlireo inches. The perforation^, which are 

 Bupposcilby the tishermon to be the work of animals, are formed in the lower part of the 

 fn)nd an<l inere:w**» in size as they jjrow older, so that the perforations are larger in 

 the npper and central parts of the frond. New holes are also formed between those 

 already formed, so that there is a ditVerence in size depending upon the age of the lioles 

 in all parts of the frond except the base. The formation of the hoh's begins l»y an 

 elevation t»f small portions of the fron<l, which a])pears as if some small point like that 

 of a pencil had been pressed against it ; at length the frond ruptures circuhirly and 

 the hob* formed is minute and above the plane of the frond. Th(^ margins of the largo 

 holes are often wavy, and when dried with a slight pressure the waviuess becomes so 

 marked as to lead one to suppose that the specimens belong to a distinct species. The 

 midrib varies considerably in breadth and occasionaly it grows out, forming a lamina 

 at right angles to the frond. The usual perforations are found in the additional 

 lamina, which sometimes grows to be as large as the original lamina. The fruit of 

 Agarum, which is incorrectly figured in the Nereis as having a form of tetraspores, 

 resembles very closely that of iMminaria. The species apparently does not bear fruit 

 on the Massachusetts coast, at least we have never been able to find any; but at East 

 port the fruit is formed as early as September. The sori are scattered irregularly over 

 the central part of the frond and are most easily seen after the frond has been out of 

 the water a short time. The sori are not so thick as in Alaria and Laminaria and the 

 paraphyses do not have so prominent a hyaline extremity as in those g«'nera. Harvey 

 states that the lamina are sometimes ten or twelve feet long, but this is probably an 

 overestimate. 



ALARIA, Grev. 



(From ala, a wing.) 



Fronds attached by a branching root-like base, stipitate, meiubrana- 

 ceous, with a distinct midrib ; fruit borne in special lateral leaflets below 

 the lamina, consisting of club shaped, one celled paraphyses and ellip- 

 soidal unilocular sporangia ; plurilocular sporangia unknown. 



A genus readily known by the small, ribless leaflets given off from the stipe below 

 the lamina, in which the the fruit is borne in the autumn. The genus inhabits the 

 colder waters of the northern hemisphere and the species sometimes attain a length of 

 fifty feet. The number of species does not exceed half a dozen, and the specific marks, 

 Biich as the shape of the midrib, the lateral leaflets, and the base of the lamina, are 



triable, so that all the species cannot be said to be well marked. 



A. E3CULENTA, Grev. (A. esaiknfa, Phyc. Brit., PI. 70. — Laminaria 

 mumfolia, De la Pyl., Ann. Sei. Nat., Ser. 1, Vol. IV, PI. 9 d.—L. Unearis, 

 DelaPyl., 1. c.,Pl. 9/.) 



Stipe cylindrical-compressed, from four inches to a foot long, a quarter 

 to half an inch wide; midrib solid, scarcely wider than the stipe; lam- 

 ina one to ten feet long or even longer, two to ten inches from side to 

 side, decurrent on the stipe, margin wavy ; fructiferous leaflets numer- 

 ou.se, shortly stipitate, three to eight inches long, half an inch to two 

 inches broad, linear-ovate or linear-spathulate. 



Var. LATIFOLIA, Post. »S: Kiii)r. {Laminaritt Pyl'tii^ Dory, in Floro 



