16 Transactions of the Society. 



II, — List of Desmids from Massachusetts, U.S.A. 



By Wm. West, F.L.S., Lecturer on Botany and Materia Medica 

 at the Bradford Technical College. 



(Bead Uth November, 1888.) 

 Plates II. and III. 



Me. John M. Tyler, of Amherst College, Massachusetts, has kindly 

 sent me a few tubes of Algse from the neighbourhood of Amherst, in 

 which I have noted the Desmids detailed in the following list. Other 

 interesting Algae were also present, with which I may deal at some 

 future time. I also tender my thanks to my son, Mr. G. S. West, 

 for much help during the preparation of this paper. Some of the 

 Desmids I believe to be quite new, and there are several interesting 

 varieties and forms. 



The figures have been drawn from nature to a uniform scale of 

 400 diameters except where otherwise stated. 



Ryalotheca dissiliens (Sm.) Breb. Frequent. 



„ „ var. hians Wolle. 



Besmidium Swartzii Ag. Sparingly. 

 Penium digitus (Ehrenb.) Breb. 

 P. ohlongum de By. 



EXPLANATION OF PLATES II. and III. 

 Plate II. 



, — Xanthidium Tylerianum nov. sp. Front view x 400. 



— „ „ „ Side view x 400. 



, — ,, „ „ End and other, views x 400. 



, „ „ „ Dividing fronds x 400. 



, —Zygospores of some desmid to wMcli no semi-cells were attached x 400. 

 . — Cosmarium pygmieum Arch. ? X 400. 



, „ Meneghinii Breb. fortxia octangularis Wille, var. ^ simplicissiinum 



Wille X 400, the right-hand fig. X 1000. 

 , — Closterium Leihleinii Kiitz., var. curtuin nov. var. X 400. 

 , — „ rostratum Ehrfnb. var. brevirostratum nov. var. x 400. 



. — „ svbdirectum nov. sp. X 400. 

 , — Docidium Trahecula (Ehrenb.) Naeg. X 400. 

 . — Micrasterias radiosa Ralfs, var. punctata nov. var. X 400. 



Plate IIL 



. — Zygospore of some desmid unattached to semi-cells x 400. 



. — Xanthidium Tyler ianum nov. sp. Dividing frond, the young semi-cells of 



which have not yet begun to develope spines, x 400. 

 . — Calocylindrus Cucurhita Kirch, x 400. 

 . — Closterium subdirectum nov. sp. X 400. 

 . — Staurastrum Sehaldi 'R.Qm&ch, three views X 400. 

 . — „ eustephanum Ralfs, two views X 400. 



. — Cosmarium Ixve Eaben., var. septentrionale Wille x 400. 

 , — Staurastrum angulatum nov. sp. X 400. 

 . — ,, spongiosum Breb. X 400. 



, — ,, Meriani Eeiusch x 400. 



. — Cosmarium Cordanum Breb. x 400. 

 . — Eutst?'um binale Ralfs, forma minor x 400. 



