14 NATURAL HISTORY SOCIETY OF DUBLIN. 



ensemble. Just as in every group of related species there appear, no 

 doubt, a number of forms more or less intimately related to one another; 

 but these, the more they are studied and their characteristics noted, the 

 more forcibly do the idiosynocrasies and the individuality of each seem 

 to force themselves upon our attention. 



In at least two places in Professor Pringsheim's memoir alluded to, 

 he promises to give to the world a detailed description of all the species 

 in this family known to him. It is greatly to be wished that he should 

 redeem that promise. But at least he seems to have indicated the plan 

 which an observer, desirous to work out this group, should follow, 

 which, if indeed it be seemingly here the only correct one, has the dis- 

 advantage that the distinctions are necessarily founded on data compa- 

 ratively so recondite, that an observer must trust to good fortune in 

 obtaining the specimens in that happy condition in which the characters 

 of the fructification are fully displayed. 



Family, (Edogonle.ze. 



Genus, Bulbochsete (Agardh). 

 Bulbochmte Pringsheimiana (sp. nov.). 



[Plate II.] 



Specific Characters. — Oospore elliptic; dwarf male plants seated 

 upon the oogonium, which they equal in length ; oogonium bearing im- 

 mediately above it the mother- cells of the androspores. 



General Description. — Oospore elliptic, orange-brown when ma- 

 ture ; dwarf male plants elongate, with "foot" and " outer," many- celled 

 antheridium, seated upon the oogonium (very rarely beneath it), erect, 

 about as long as the oogonium; septum very high up in the cell sup- 

 porting the oogonium, sometimes so close thereto as almost to appear as 

 if absent ; oogonium bearing immediately above it the mother-cells of 

 androspores, aperture (micropyle) of the oogonium very close to its 

 upper end; plant rather slender, cells averaging between twice and 

 thrice as long as the broadest diameter ; growth unilateral. 



Affinities and Differences. — It will be noticed that this plant falls 

 under the subdivision of the genus with elliptic oospores, all which are 

 characterized by Pringsheim as having the dwarf male plants, which 

 are here throughout of the structure called by him " outer" and with a 

 " foot," seated always near to, but never on, the oogonium. Now, the 

 present plant seems to be sufficiently characterized by having mostly a 

 single dwarf male plant seated on the oogonium, upon which it stands 

 vertically; sometimes there are two upon one oogonium. Thus this 

 plant presents in this respect a striking, and indeed as yet the only 

 known, exception to the character as laid down by Pringsheim, and this 

 circumstance alone would seem to mark it out as distinct. It agrees, 

 indeed, with the other elliptic- spored species in the dwarf male plants 

 having a "foot" and " outer" antheridium. But it differs from them by 

 the circumstance of the oogonia being immediately surmounted by the 

 mother-cells of androspores, all the other elliptic- spored species de- 

 scribed bearing above the oogonia either ordinary vegetative cells or 



