Desmidiea.'} infusorial animalcules. 255 



CosMARiUM cristatiim. — Orbicular, deeply constricted, margined by 

 papilla- like pearly granules ; end \'iew linear, ^yitb an inflation at 

 tlie middle of each side. (1 -700th.) 



t f Frond Smooth. 



C. Plmscolus. — Segments smooth, reniform ; notch linear on each 

 side; end view elliptic, Avith a slight projection at the middle of each 

 side. Larger than C. hioculatum ; and its segments are reniform, 

 and the notches linear, not gaping. (1 -687th.) 



C. Fapilio. — Segments smooth, ti-iangular, with rectangular apex ; 

 end view linear with a lobe at the middle of each side. This species, 

 named by Meneghini, is appended by Mr. Ralfs to those known to 

 liimsclf, and appears to fall under this sub-section. 



3. Constriction not forming linear notches at the sides; end view 

 circular. 



t Frond rough with pearly grunules, which give a denticulate a/ppea/r- 

 ance to the outline. 



C. cylindricum. — Segments granidated, sub-quadrate in front view ; 

 broadest at the extremity ; minute, cylindrical, about twice as long 

 as broad. (l-588th.) 



C. orhiculatum. — Minute ; segments spherical, granules wanting on 

 the neck-like contraction between the segments. Transverse view 

 has a large central opening. 



1 1 Frond smooth. 



C. moniliforme = Tessarthra moniliformis, (Ehr.) — Segments sphe- 

 rical, smooth. 



Var. fa. J — Segments united without the intervention of a neck. 



Var. fb.J — Segments united by a distinct neck. (P. 2, figs. 105, 

 106.) 



C. connatum. — Segments punctate, each about two-thii-ds of a 

 circle, uniting by their plane surfaces ; fronds slightly constricted at 

 the middle. Very large (l-285th.) 



C. Cucurlita (?) = C. Palangula, (Breb.) — Minute, sub-cylindrical ; 

 punctate, slightly constricted; rounded at the ends. (l-586th.) 



C. Thwaitesii. — Cylindrical ; constricted ; ends rounded ; puncta 

 very indistinct, two or three times longer than broad. It diifers 

 from (7, Cucurlita in its larger size and indistinct puncta ; from C. 



