18 



L. trilaminotv, Har. ; Stoningion. 

 L. digitula, Lamour. ; Seaconnet. 



III. Chorda. Stack. 

 Frond cylindrical. Spores conical, covering the whole surface. 

 C.Jifum, Lamour. ; Long Island Sound, &c. 

 C. lomenturiu, Grev. ; Seaconnet. 



Order IV.— DICTYOTACEjE. 

 Inarticulate. Spores superficial and in lines. Hoots coated with 

 woolly fibres. Containing nine American genera. 

 I. Padina. Adanson. 

 II. Zonaria. — Name, a girdle or zone. 

 Ill Dictyola. Lamour. — Name, a net. 

 IV. DictvoHphon. Greville — Same, a net and a tube. 

 V. Punciana. Greville — Same, a dot. 

 Vf. Asperococcus. Lam. — Name, rough seed. 

 VII. DictyosphaBria. 

 VIII. Halodictyon. 

 IX. Litosiplion. Harvey. — Name, a slender tube, 



I. Padina. Adanson. 



Frond ribless, fan shaped, with concentric lines, edged with 

 articulaied filaments Spores bursting through the cuticle of the 

 upper surface. 



1. P. povor.ia, Lamour ; Florida. 



II Zonaria. 



Frond flat, fan-shaped, ribless. Cleft, concentric lines. Scat- 

 tered sori, bursting through ihe cuiiclj of both sides. 

 I. Z. Sp 1 or new; Key West. 



I'll. Dictyot*. Lamour. 



Frond ribless, linear, dicholomons. Koois coated with woolly 

 fibres. Fructification, in scattered Hues, bursting through the 

 cuticle on both sides. 



D. dichotnma, Hudson ; Florida. 



J), ci/iofu, Ag. ; Kev West. 



1). Unions ; Key West 



I). Sp. ? or new; New York Hay. 



D. Sp. ? or new ; Long Island Sound. 



IV. Dicn osjpuon. Grev. 



Frond thread-like, tubular, branched. Spores naked, scattered 

 over the surface. 



D.JcBciculactus, Hudson ; N. Y. Bay and L. 1. Sound. 



V. Punctaria. Grev. 

 Frond leaf-lil e, no midrib Spores scattered over the whole sur- 

 face in minute duts. 



