WITH NOTES ON OTHER SPECIES. Ill 



Massachusetts — Cambridge and Wood's Holl, Trelease. Europe. 



I have never had the opportunity of studying this species alive, and hence arises 

 the necessity for referring to DeBary's description ('88) for some details. It 

 occurs in preparations made by Prof. Trelease from cultures made in Eastern Massa- 

 chusetts, and must therefore be included in our flora. It has hitherto been the only 

 known member of the genus with spiny oogonia, and is readily distinguished from 

 the second such species, next to be described, by its globular and few-spored oogonia, 

 borne on slender threads. 



Saprolegnia Treleaseana sp. nov. 



111. : PI. XVII, Figs. 56-59. 



Hyphse very thick. Zoosporangia cylindric, rare. Oogonia terminal or inter- 

 calary, on main hyphse, elliptical or globular, when terminal usually ending in a 

 strongly developed apiculus ; their walls not pitted, but with rather scattered blunt 

 outgrowths of varying length, oftenest short. Antheridial branches short and slen- 

 der, arising just outside the oogonial wall, one or several to each oogonium, or 

 sometimes wholly absent. Antheridia short-cylindric or slightly clavate. Oospores 

 numerous, averaging ten or twelve in an oogonium, centric, their diameter from 25 

 to 35/x. 



Massachusetts— Wood's Holl, Trelease. 



It is a great pleasure to dedicate this very striking species to its discoverer, 

 Prof. William Trelease, of St. Louis, whose early studies of our Saprolegniacece were 

 unfortunately cut short by other engagements. This is done as a slight acknowledg- 

 ment of the valuable additions to the present paper which are due to his generosity, 

 and in recognition of the high character of his work as a botanist. 



The species was obtained by him in 1881 in cultures with material fi-om Wood's 

 Holl, Mass., and he has communicated all his notes and material to the vvriter. It 

 has very coarse and freely branched hyphse which often considerably exceed 100//. in 

 diameter at the base. The sporangia are so rare that Prof. Trelease observed 

 only one (Fig. 56), and I have been unable to find any in his material. The size 

 and manner of branching of the hyphse, as well as the appearance of the oogonia, 

 strongly suggest the genus Achlya, but the single sporangium seen showed that the 

 spores escape as in Saprolegnia. In the structure of its sexual organs this plant 

 resembles quite strikingly that to be described later as AcJilya papillata, but it is 



A. p. S. — VOL. XVII. o. 



