130 FRESH-WATER ALGLE OF THE UNITED STATES. 



always branched ; the branches placed a little below the top of 

 their supporting cells ; 2d, the rhizoid part developed, from the 

 germinating spore downward, almost always sterile and branch- 

 less, commonly unicellular. Spores neutral, quiescent (agamo- 

 hypnospores), generally cask-shaped, single, formed by division 

 into two of the cauloid cells, of the chlorophyl -filled and com- 

 monly widened upper parts of these cells ; in germinating, as a 

 rule, dividing into two cells, the one giving rise to the cauloid 

 and the other to the rhizoid part of the thallus. 



Prof. V. B. Wittrock has prepared an elaborate Mono- 

 graph, " On the Development and Systematic Arrangement 

 of the Pithophoracete ; a New Order of Algce." It is fully 

 illustrated; contains 80 pp. For full and interesting details 

 consult the Monograph. 



Genus 24, PITHOPHORA, Wittr. 



Character and features the same as of the subsection given 

 above. 



PITHOPHORA OEDOGONIA, (Mont.) Wittr. 

 Var. VAUCHERIOIDES, (Wolle) Wittr. 



The stem, or cauloid part of the thallus in fertile speci- 

 mens on an average 65 ^ thick, with partly solitary, partly 

 opposite branches of two and more, rarely three degrees ; 

 sporal branches rather common ; spores usually single, but 

 sometimes twin, partly inclosed, partly terminal; the in- 

 closed spores cask-shaped, on an average 95 ^ thick and 220 /* 

 long ; the terminal spores cask-shaped, on an average 80 /* 

 thick and 220 ^ long, with the upper end conical, apex 

 rounded. 



The type of this species was collected in Guiana, and all 

 of the species of this genus were supposed to be tropical 

 plants. The variety originally found in a sterile state, had 

 the branching characteristics of a Cladophora, and the long 

 unicellular divisions of a Vaucheria, hence the name. Later 

 gatherings were full of cask-shaped spores, and changed the 

 generic position of the plant. It was found in successive 

 years in a small pond, here, Bethlehem, Pennsylvania, and 

 in three localities within a circuit often miles around Plain- 

 field, New Jersey. It is a somewhat near approach to P. 

 Oedogonia, but differs in size, being slightly more slender, 

 and in minor details. 



