THE GREEN ALGAE OF NORTH AMERICA 373 



1. V. VENTRICOSA J. G. Agardh, '1886, p. 96; Murray, 

 1893, PI. XIII, figs. 6-10 ; Vickers 1908, p. 21, PI. XXIII. A. 

 Frond solitary, saccate, spherical to pyriform, usually 2-3, rarely 

 5 cm. diam. ; secondary cells formed chiefly at the base for pur- 

 poses of attachment ; membrane smooth, translucent, showing 

 the light green contents. W. I. 



Practically unmistakable for any other species ; Halicystis 

 ova/is, the only one that it resembles, being smaller and an in- 

 habitant of quite different regions. The fronds are usually 

 about the size of a large cherry, but Murray has dredged 

 specimens " as large as a hen's egg." 



2. V. UTRICULARIS Agardh, 1822, p. 431 ; Kiitzing, 1856, 

 PI. LXXXVI, .fig. 2b-e; Wittr. and Nordst., Alg. Exsicc., 

 No. 953. Cells stout, cylindric-clavate, with similar prolifera- 

 tions ; lower parts of frond decumbent, or creeping among other 

 algae, then erect, up to 5 cm. high, often forming dense tufts ; 

 membrane dark green, shining ; zoospores biciliate. Fig. 138. 

 Bermuda, Bahama. Europe. 



Growing from the litoral zone to a depth of 2 m.; in the 

 former station the filaments are shorter and stouter ; in the lat- 

 ter longer and more slender. 



3. V. AEGAGROPILA Agardh, 1822, p. 429; Kiitzing, 1856, 

 PI. IvXXXVII, fig. i ; P. B.-A., No. 772. Fronds much and 

 irregularly branched, cells subcylindrical, rather short, 2-3 mm. 

 diain., forming a dense, globular tuft; membrane rather dull. 

 W. I. Mediterranean, Indian, Pacific Oceans. 



Nearly allied to V. utricnlaris, but with more slender, less 

 clavate cells, and forming denser masses, soon freed from the 

 substratum and floating in shallow water. 



4. V. VERTiCiivivATA Kiitzing, 1849, p. 508 ; 1856, p. 30. PI. 

 LXXXVIII; Vickers, 1908, p. 21, PI. XXIII. B ; P. B.-A., 

 No. 1533. Cells .cylindrical, straight, 2-3 mm. diam., -producing 

 whorls of similar cells below the obtuse apex ; branching re- 

 peated, forming tufts about 5 cm. high ; membrane very deli- 

 cate and translucent. W. I. 



The regular and frequent whorled branches distinguish this 

 from all our other species ; dried specimens adhere to paper 

 more firmly than in other species. 



5. V. CONFERVOIDES Harvey, Alg. Ceylon Exsicc., No. 

 73 ; Wittr. and Nordst., Alg. Exsicc., No. 349. Fronds decum- 

 bent at first, then ascending, cylindrical, 2-3 mm. cliam., simple 

 below, above branching sparingly, usually 3-4 branches in a 



