BATKACriOSPEEMEiE. 61 



This genus scarcely differs from TJlva on the one side and Palmella on the other. 

 The frond is more gelatinous that in Ulva ; and more membranous than in Palniella. 

 The whole of the endochrome is converted into spores, which are arranged in squares 

 and more distantly placed than in Ulva. 



1. Tetraspoka lacunosa, Chauv. ; frond at first tubular, then flat, or irregularly 

 lobed, membranaceo-gelatinous, pale -green, everywhere pierced with roundish holes of 

 various sizes. Chauv. Alg. Norm. Breb. Alg. Fal. p. 11, t. 1. Kiltz. Sp. Alg. p. 

 227. T. Godeyi, De Breb. Kiitz. Tab. Phyc. t. 30,/. 3. T. perforata, Bailey, M.S. 



Hab. In fresh-water streams. Abundant near Westpoint, Prof. Bailey. Providence, 

 Rhode Island, 3fr. Olney. (v. s. in Herb. T.C.D.) 



Frond at first funnel-shaped, afterwards splitting open, and then flat, expanding 

 upwards and irregularly lobed, everywhere pierced with roundish holes of various sizes, 

 large and small intermixed. These holes increase in size and numbers with age, and 

 thus at last the frond becomes an open network. The substance is very gelatinous, but 

 rather firmer than in some other species of the genus. The colour is a pale gx'een ; and 

 the hyaline gelatinous membrane is filled with roundish granules set in fours. 



Kiitzing's figure of T. Godeyi answers well to our plant. I have not seen any 

 authentic specimens of T. lacunosa, which is referred by Kiitzing to his T. lubrica, 

 var. /9., but the description given of it applies to the American plant. When carefully 

 dried, it forms a very pretty object for the Herbarium. 



Order Y.— BATRACHOSPERME^. 



Batrachosperme^, Ag. Syst. p. 23, (partly) Harv. Man. Ed. 1, p. 119- Berk. 

 Crypt. Bot. p. 136, Dne. class, p. 33 (partly.) Kiitz. Sp. Alg. p. 535. Lemaniece, 

 Ag. Sp. Alg. 2, p. 1. Harv. Man. Ed. 1, ;?. 118, Dne. Class, p. 3], Kiitz. Sp. 

 Alg. p. 527 (partly.) 



Diagnosis. Blackish-green, olivaceous or purplish fresh water Algge, with filiform, 

 branching, inarticulate fronds, composed of small cells ; naked, or whorled with monili- 

 form ramelli. Fructification ; moniliform strings of naked spores, either forming 

 external tufts, or concealed within a tubular frond. 



Natural Character. Boot merely a point of attachment or little disc, by which the 

 frond is firmly fixed to the substances (usually rocks and stones in rapid rivers and 



