WITH NOTES ON OTHER SPECIES. 121 



only by those of A, megasperma, and may reach, in extreme cases, a diameter of 

 rather more than 40/y.. I have not observed the tendency towards the excentric type 

 of oospore said by DeBary to be sometimes shown by this species in the one-sided 

 position of the oil-globule. 



This plant shows some striking affinities with A., megasperma and A. jpolyandra ; 

 and, while in some respects intermediate between them, seems to take the position 

 here given it with less violence to all considerations. 



AcHLYA OBLONGATA DcBary ('88). 



111. : DeBaiy, '88, PI. X, Figs. 7-9. 

 PI. XIX, Figs. 87-89. 



Hyphse stout. Zoosporangia slightly fusiform, not abundant. Oogonial branches 

 short or rarely somewhat elongate, straight, racemosely arranged, Oogonia occasion- 

 ally intercalary, usually terminal, and elliptical, ovate, or obovate, rarely globular, 

 with smooth, unpitted walls. Antheridial branches slender, of strictly diclinous 

 origin, sometimes branched. Antheridia on every oogonium, numerous and small, 

 short-clavate. Oospores fi'om one to twenty, usually seven to nine, in an oogonium, 

 centric, their average diameter about 21 ii. 



Massachusetts — Amherst : Louisiana — St. Martinville and Bayou Tortue, 

 Langlois. Europe. 



The elongate oogonia and diclinous hyphse readily separate this type from all 

 other Achlym, no other diclinous species being known except A. 'prolifera. It has 

 occurred in cultures from Mill river, in Amherst, and from the aquatic room of the 

 Plant-house of the Massachusetts Agricultural College, as well as in two cultures 

 from Louisiana. The oogonia, which are typically rounded at their apices, show a 

 tendency to a pointed form in some Louisiana specimens (Fig. 88) ; while in all cul- 

 tures some of them are of a distinctly globular form, especially such as terminate 

 principal hyphse. 



The oospores commonly do not occupy the whole interior of the oogonium, but 

 are collected into a group at one side, leaving an empty space. I do not, however, 

 find them " viel kleiner als die aller Yerwandten," as they are said by DeBary ('88) 

 to be. 



In the form and size of its antheridia and the delicacy of its antheridial branches 

 as well as in its strict dicliny, the species strongly recalls S. dicUna., but the resem- 

 blance goes no further. 



