V. SPH.EROCOCCOIDEiE. 101 



Douglas' and Coulter's specimens, where the mai'gin is uninjured, they are congre- 

 gated in large, dense, linear intra-niarginal sori, extending along the sides of the 

 laciniaj. Toward the apices the sori are linear, branching and anastamosing, as in 

 Hymenma ; and all three characters of sorus, the simply intermarginal, the branching 

 and anastamosing, and that placed in the extramarginal leaflet, may sometimes be 

 found on the same root ! The existence of such specimens considerably weakens 

 the claims of B. Binderianum to specific distinction. 



Plate XXI. A. Fig. 1. Botryoglossum platycarpum, the natural size. Fig. 2, 

 marginal leaflet, with sorus ; fig. 3, a tetraspore ; fig. 4, portion of the areolated 

 surface ; fig. 5, section through the frond ; the latter figures magnified. 



IV. HYMENENA. Grev. 



Frond rosy red, expanded, irregularly laciniated, unsymmetrical, membranaceous, 

 areolated, without midril), but everywhere traversed with numerous prominent, 

 anastomosing, subparallel nerves. Coneepfades sessile on the nerves, depressed in 

 the centre (umbilicate), with an orifice ; walls very thick ; placenta basal, slightly 

 prominent, crowned with a depressed tuft of dichotomous spore-threads whose ter- 

 minal cells are earliest ripened. Tetraspores tripartite, in long linear sori lodged 

 in the spaces between the nerves, or in marginal leaflets. 



This genus, which is perhaps too closely related to the preceding, chiefly differs 

 in the absence of midrib, and in the numerous anastomosing nerves which supply 

 its place. It is distinguished from Nitophyllum by the form of the conceptacle and 

 the thickened substance. The linear disposition of tetraspores occurs in the three 



1. Hymenena _yissa, Grev. ; frond palmate, the laciniaa linear-cuneate, undulate, 

 obtuse, erect, very entire at the margin. Harv. Ner. Austr. p. 118, t. 44. Kiitz. 

 Sp. Alg. p. 873. J. Ag. Sp. Alg. 2, p. (374. Fucus venostis, Turn. Hint. t. 138. 



Hab. Monterey, California, Capt. Beechey ; Capt. Wilkes, (v. v.) 



Root branching. Fronds six to twelve inches high, palmate, or irregularly 

 dichotomous, broadly cuneate in outline. Lacinice linear-oblong, simple or lobed, 

 undulate, with an entire margin. Every part of the frond is traversed by closely 

 placed, longitudinal, anastomosing prominent ner\'es, on which the conceptacles are 

 formed, and between which the tetraspures are scattered in long lax sori. The 



