AllCIIERj ON A NEW SPECIES OF ANKISTRODESMUS. 255 



Affinities and diiferences. — The scarcely spiral, sometimes 

 scattered^ cndoclirome, at first made mc hesitate to consider 

 this plant as belonging to Spirotoenia ; but as it frequently 

 seems to form an oblique parietal band, and the self-division, 

 as in other species of the genus, is oblique, and the divided 

 fronds held together by a gelatinous investment, there can, 

 I apprehend, be no doubt but that in this genus this minute 

 little form finds it proper location. Moreovei', I have seen 

 so»2e specimens in which the endochrome clearly made a spiral 

 turn, though in the majority of instances the condition I have 

 tried to describe above is seen ; and not unfrequently, as in 

 other species, a confused or irregular condition of the endo- 

 chrome exists. Its very minute size, subacute extremities, 

 and without a clear space, easily distinguish this from other 

 described species of Spirotaenia. It really appears to approach 

 more to Endospira closteridia, Breb., Kg. (which plant, as 

 I before stated, I apprehend should fall under this genus) ; 

 but it is distinguished by its fusiform, not at all arcuate, and 

 by its narrow, outline, as well as by its obscurely convoluted, 

 not distinctly and smoothly spiral, endochrome. 



On a New^ (?) Species of Ankistrodesmus (Corda), tvith 

 Remarks in connexion therewith as regards Closterium 

 Griffithii (Berk.) and C. subtile (Breb.). By William 

 Archer. 



I HAVE, on the present occasion, to draw attention to a very 

 minute organism, but which, indeed, so far as I can see, I can 

 scarcely allude to as a new species ; for I conceive that it has 

 been more than once previously described, but I think I shall 

 be able to render it probable tliat it has been so under an 

 erroneous designation. Of course, the truth of this assump- 

 tion depends on my being right as to the identity of my plant 

 with that of the authors alluded to, as well as upon my own 

 proper appreciation of its characteristics and the correctness 

 of my own conclusions in regard to them. I shall now, how- 

 ever, give the characters of the plant according to my own 

 view, adopting, in doing so, the same mode that I have done 

 in other species, reserving the reasons why I venture to differ 

 from those who have previously described what, as I before 

 stated, I conceive to be one and the same organism, for the 



