V. SPH.ER0C0CC0IDEJ5. 93 



walls are tliin ; the sporiferous nucleus depressed, not filling the cavity ; the spores 

 ellipsoidal, the terminal ones ripening much earlier than the rest. Tetraspores tri- 

 partite, immersed in fleshy, prominent warts, variously lobed and distorted. Colour 

 a brilliant lake-red, quickly becoming orange and soon perishing in fresh water. 

 Substance very thin. Surflxce areolated with large hexagonal cells. In drying, it 

 closely adheres to paper. 



Plate XXI. B. Fig. 1. Grinnellia Ammcana, the natural size. Fig. 2 and 3, 

 conceptacles of diflferent forms ; Jig. 4, a conceptacle divided vertically ; Jig. 5, 

 spore-threads ; fg. 6, a wart with tetraspores ; Jig. 7, the same, divided vertically ; 

 fig. 8, a tetraspore ; all more or less magnified. 



II. DELESSERIA. Lamour. Grev. ref. 



Frond rosy-red (very rarely purple), leaf-like, laciniate or branched, delicately 

 membranaceous, areolated, symmetrical, traversed by a percurrent midrib. Concep- 

 tacles sessile on the midrib or on a lateral nerve, globose, without orifice : placenta 

 basal, more or less prominent, crowned with a pulvinate tuft of simple or subdicho- 

 tomous spore-threads whose terminal cells are earliest ri2:)ened : spores elliptical or 

 roundish. Tetraspoi'es tripartite, grouped in definite spots or sori, occupying por- 

 tions of the frond or of separate leaflets. 



"With the exception of D. sanguinea, Ag. which has a sporiferous nucleus of a 

 very difi"erent structure and now forms the genus Wormskioldia of J. Agardh, I 

 retain most of the species included in Dr. Greville's restriction of the genus. By 

 Kutzing these are arranged in his genera Phycodrys and Hypoglossum, groups 

 which I regard as subgenei'a only. The species are numerous and many of them 

 are widely dispersed. Of the following, D. tenuifolia and D. involvens, now first 

 described, have been found only on the Florida Keys. 



Sub-genus 1. Phycodrys, Kutz. Frond pAnnatifid or sinuated. 



1. Delesseria sinuosa, Lamour.; stem (at length) elongated, branched, beset with 

 oblong or obovate, deeply sinuated or pinnatifid, toothed, penni-nei'vcd leaves ; 

 nerves opposite. Harv. Phyc. Brit. t. 259. J. Ag. Sp. Alg. 2, p. 691. Phycodrys 

 sinuosa, Kiitz. Sp. Alg. p. 874. Fucus sinuosus, Turn. Hist. t. 35. E. Bot. t. 822. 



Hab. Arctic Sea Coast, Mr. Seeman. Halifax, W. II. H. Boston Bay, 3Ir. 

 Emerson, Dr. Durkee, Sfc. Newport, Prof. Bailey, Mr. Olney, ^r. 



