36 MICROSCOPICAL OBSERVATIONS. 



DESCRIPTION 



OF THE NEW SPECIES, REFERRED TO IN THE PRECEDING LIST?. 



DESMIDIEJE. 



1. COSMARIUM DEPRESSUM, B. PI. ], fig. 1. Elliptical, binate, division in the 

 plane of the longest axis. Segments entire, nearly twice as long as broad, 

 rounded above, very much flattened at base. 



Hab. Lakes in Florida. 



This species resembles C. bioculatum, Breb., but the segments are much 

 closer together, and are angular, not rounded at the nasal extremities. 



2. DIDYMOCLADON? CERBERUS, B. PI. 1, fig. 15 a lid 16. Small, deeply con- 

 stricted, segments three-lobed, lobes with four teeth, two of which project 

 upwards and two downwards at each truncated angle. 



Hab. Lakes in Florida. 



3. DIDYMOCLADON? LONGISPINUM, B. PI. 1, fig. 17. Large, smooth, triangular, 

 with two long spines at each angle. 



Hab. Lakes in Florida. 



The two last species are not very nearly allied to each other, nor to the typi- 

 cal D. furcigerus, yet they agree better with the verbal characters of the genus 

 than with those of any other known to me ; I therefore refer them here provi- 

 sionally. 



4. DOCIDIUM HIRSUTUM, B. PL 1, fig. 8. Segments many times longer than 

 broad, slightly inflated at base, surfape hirsute. 



A small species resembling D. Ehrenbergii in form, but strongly hirsute on its 

 outer surface. 



Hab. Lakes in Florida, at Enterprise. 



5. DOCIDIUM UNDULATUM, B. PI. 1, fig. 2. Segments eight to ten times longer 

 than broad, constricted six to eight times at regular intervals throughout their 

 entire length, with the base and ends crenate. 



Smaller than D. nodulosum, Breb., with more frequent and deeper constric- 

 tions. The same characters distinguish it from D. nodosum and D. con- 

 st ric turn, B. 



