Derepyxis amphora Stokes 1885, p. 318 



PL 96, Fig. 21 



Lorica broadly ellipsoid, on a short stipe, gradually narrowed 



anteriorly to form a short, relatively wide neck; protoplast ovoid, 



with 1 or 2 parietal chromatophores; lorica 12.9-14ju, in diameter, 



31-35/A long. 



Attached to filamentous algae; common. Mich., Wis. 



Derepyxis dispar ( Stokes ) Senn 1900, p. 161 

 PI. 95, Fig. 34 

 Lorica sessile, vase-shaped, inversely ovoid, abruptly narrowed 

 above to form a slender neck; protoplast globose, suspended on a 

 cross partition of the lorica; flagella about twice the length of the 

 protoplast; lorica 10-14/x in diameter, 18-20/^ long; neck 1-2^ wide, 

 5/x long. 



Attached to filamentous algae in tychoplankton of acid swamps 

 and shallow lakes. Mich., Wis. 



FAMILY SYNURACEAE 



In this family the cell membrane is beset with silicious scales 

 which form projecting barbs, especially near the anterior end. Only 

 the free-swimming colonial genus Synura is represented in our 

 region. 



SYNURA Ehrenberg 1838, p. 60 



A free-swimming globose colony of pyriform cells radiating from 

 a common center, with the broader end directed outward; cell 

 membrane furnished with short spines or apiculations formed by 

 spirally arranged scales, especially evident in the anterior region; 

 chromatophores 2 parietal plates, laterally disposed; flagella 2, of 

 equal length, arising at the anterior end; eye-spot lacking. 



Key to the Species 



Cells pyriform, densely arranged in ovoid 



or spherical colonies — - S. uvella 



Cells elongate-pyriform (club-shaped), not compactly arranged 

 but rather loosely disposed in a radiating fashion in spherical 

 or obovoid colonies S. Adamsii 



Synura Adamsii G. M. Smith 1924, p. 136 



PI. 92, Fig. 1 



A free-swimming, globose colony of rather loosely arranged, 



elongate-pyriform or club-shaped cells, much narrowed to subacute 



at the posterior end; anterior end broadly rounded and furnished 



[375] 



