104 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 



and which is found floating and infertile in the course of the Gulf Stream and in the 

 so-called Sargasso Sea, hetween 20° and 43<* N. and 40° W. It is rarely washed ashore 

 in New England, but is frequently brought in by fishing vessels. It is said that there 

 is a large mass of this sea-weed in the ocean not far from Nantucket, but there is no 

 definite information on the subject. The species in its floating form is distinguished 

 from the last by its narrower leaves, destitute of cryptostomata, its darker color, and 

 denser habit. 



Suborder VAUCHERIE^. 



Comprising a single genus, Yaucheria, whose characters are given 

 below. 



VAUCHERIA, D. 0. 



(Named in honor of Jean Pierre Vaucher, of Geneva.) 



Fronds green, unicellular, composed of long, irregularly or falsely 



dichotomously branching filaments, monoecious or dioecious; oogonia 



sessile or stalked, containing a single oospore ; antheridia either short 



ovoid sacks or formed at the tips of branches, which are frequently 



spirally twisted; antherozoids very small, with two cilia; non-sexual 



reproduction by very large zoospores, which are covered with cilia, or by 



motionless spores formed at tbe ends of short branches. 



The Vaucheriw abound both on our coast and in inlaud waters, and some species 

 grow upon damp ground in gardens and meadows. They either form thick turfs of a 

 dark-green color when growing in places which are not constantly submerged, or else 

 extend in indefinite-shaped masses when growing where there is plenty of water. 

 They are generally easily recognized at sight, and are known under the microscope 

 by the long branching filaments of a deep-green color, destitute of cross-partitions 

 except when the fruit is forming. Although very abundant on our shore, the species 

 are little known, because the specific characters depend upon the fruit. The deter- 

 mination of sterile specimens is out of the question, and, even when fruiting, dried 

 specimens are of comparatively little value. A considerable number of species of 

 Vauckeria have been described, but as a great part of them have been described from 

 individuals bearing the non-sexual spores only, recent writers, as Walz and Nordstedt, 

 have reduced the number of species very much by omitting imperfectly characterized 

 forms. Nordstedt admits nineteen species in Europe. The American species have 

 never been critically studied. Specimens should be kept in fluid rather than mounted 

 on paper, and sketches of the fruit should be made at the time of gathering. It 

 should not be forgotten by the collector that some of the species are dioecious, and 

 also that a species is not perfectly known unless the non-sexual spores are described 

 as well as the oospores. 



V. Thuretii, Woronin, Beit, zur Kenntniss der Vaucherien, in Bot. 

 Zeit., Vol. XXVII, p. 157, PI. 2, Figs. 30-32. 



Monoecious; filaments .03-8 mm in diameter, forming short, dense turfs; 

 antheridia sessile, oval, .05-7 mm broad by .10-14 mm long; contents of 

 antheridia colorless ; oogouia either sessile or on short lateral branches, 

 obovoid or pyriform, inclined, .25-30' mm long by 20 mm wide ; oospores 

 spherical, .15-18 mm in diameter, yellowish brown; cell-wall rather thin; 



