52 Minnesota Algae 



ii6. Hyella fontana Huber and Jadin. Sur une nouvelle Algue per- 

 forante d'eau douce. Journ. de Bot. 6: 285. pi. 11. 1892. De Toni. 

 Syll. Algar. 5: 126. 1907. 

 Collins, Holden and Setchell. Fhyc. Bor.-Am. Fasc. 7. no. 303. 1897. 



Collins. Some perforating and other Algae on freshwater shells. Erythea. 5: 



95. 1897. 



Plate III. fig. i3. 



Colonies immersed in substance of shell, dark gray or bright blue, 

 often very dense and then through division of cells having the aspect of 

 Chroococcus, or loosely branched; integument almost invisible; vegetative 

 cells S-io mic. in diameter, two to four times shorter than wide; gon- 

 idangia usually larger and more nearly spherical than the vegetative cells. 



Connecticut. In shells in company with Plectonema terebrans, 

 G'Omontia holdenii. "Twin lakes, Salisbury, Litchfield county. Au- 

 gust 1895. (Setchell and Holden). 



"Scattered through the shells, sometimes in rather dense, chroococ- 

 coidal masses, sometirnes in loosely branching filaments." — Collins. 



Genus DERMOCARPA Crouan. 

 Ann. Sci. Nat. Bot. IV. 9: 70. 1858. 



Colonies usually epiphytic, forming a somewhat indefinite layer; cells 

 spherical, egg-shaped, pear-shaped, oval or oblong, solitary or united in 

 a layer; cell contents usually blue-green or violet; reproduction by means 

 of gonidia formed by simultaneous division of contents of the gonidangium; 

 gonidangia oval or elongate, dissolving at apex to allow the scape of the 

 gonidia. 



I Cells somewhat oval or oblong, not contracted at base to form a stalk. 



1 Cell contents blue-green, green, olive or brown D. prasina 



2 Cell contents rose-colored or violet 



(i) Cells 4-5 mic. in diameter D. rosea 



(2) Cells 8-28 mic. in diameter D. violacea 



II Cells contracted at base to form a stalk. 



1 Colonies dark violet-brown; cells 18-25 mic. in diameter, 40-60 mic. in 



length D. fucicola 



2 Colonies irregularly outlined; cells 8.5-11 mic. in diameter, 16.5-33.5 



mic. in length D. smaragdinus 



3 Colonies minute; cells 9-5-17 mic. in diameter, 13-25 mic. in length 



D. olivaceus 



4 Cells 18-24 mic. in diameter, 17-24 mic. in length 



D. leibleiniae 

 var. pelagica 



117. Dermocarpa prasina (Reinsch) Bornet and Thuret. Notes Algolo- 

 gique. 2: 73-77. pi. 26. f. 6-9. 1880. De Toni. Syll. Algar. 5: 128. 

 1907. 



