Ulothrix 153 



so as to show any particular difference between their chromatophore 

 characters. It is also generally difficult to find authoritative points 

 of separation in the original descriptions of such fine species. 



In the description, however, of U. variabilis, the following 

 phrases are used : " nucleis cellularum quadratis saepius angustis 

 pectinatim dispositis " (Kiitzing, '49). " Zellinhalt aufangs genau 

 quadratisch " (Rabenhorst, '63), and " cytioplasmate initio semper 

 quadrato-contracto (Rabenhorst, '68). Now the chromatophore 

 of the form identified above as this species would hardly be called 

 square, but it is generally contracted and placed on one side of the 

 cell. Furthermore, so far as one can judge from the illustration 

 given by Kiitzing ('52), our specimens conform to his species. 



We believe, therefore, that there is no question as to the cor- 

 rectness of the above description for U. variabilis and of the dis- 

 tinctness of this form from U. subtilis (= Stichococcus subtilis 

 Klerck.). There is certainly no question as to the specific dis- 

 tinctness of the two forms above described from that which is 

 hereinafter identified as Stichococcus subtilis. 



Illustrations like that of Wittrock ('83) for this species and 

 that of Wille ('85) for U. variabilis f. marina, in which the chroma- 

 ophore has a homogeneous, square appearance, were undoubtedly 

 made from material not well preserved. They show exactly the 

 similarity of appearance which is to be found in dried specimens 

 of small forms of Ulothrix and Stichococcus. 



7. Ulothrix implexa (Kiitz.) Kiitz. Spec. Alg. 349. 1849; Tab. 



Phyc. 2: pi. 94. f 2. 1852. Hauck ; Rabenh. Krypt. Flor. 



Deutschl. 2: 440. 1885. Reinbold, Schrift. Nat. Ver. 



Schles.-Holst. 8 : 129. 1889. Batters, Trans. Berwick. Nat. 



Club, — (35). 1889. Foslie. Tromso Mus. Aarsh. 13: 143. 



1890. Collins, Bull. Torrey Club, 18 : 336. 1891. 



Hormidium implexum Kiitz. Bot. Zeitung, 5 : 177. 1847. 



Ulothrix Ligustica Dufour, Erb. Critt. Ital. I. 1032 {fide De 

 Toni). 



Bangia ? confervoides Zanard. Atti R. 1st. Ven. 6 : 249. pi. 2. 



1847. 



Ulothrix? confervoides DeToni & Levi, L'Algarium Zanardini, 



134- 1 



