148 DESCRIPTION OF [Polyyastrica. 



glands dispersed, or placed in a number of series ; rays 

 obscure. Found among oscillatoria. Length 1-1 40th to 

 l-60th. 



109. CLOSTERIUM digitus. The finger-shaped Clos- 

 terium. Lorica smooth, straight, ovato- cylindrical, four 

 times as long as broad, and considerably rounded at the 

 ends. Traces sometimes of a triple self-division, and 

 longitudinal fillets undulating along the edges. Found 

 amongst conferva. Length 1 -240th to 1-1 20th. 



110. CLOSTERIUM attenuatum. The slender-formed 

 Closterium. Lorica smooth, crescented, or slightly curved, 

 and tapering considerably towards the extremities, which 

 are obtuse ; glands in a single series along the middle, 

 with no central transverse rays. Length l-48th. 



111. CLOSTERIUM cornu. The horn-shaped Closterium. 

 Lorica smooth, very slender, slightly curved, and ap- 

 proaching to cylindrical, with the apices truncated. Fillets 

 green, undulating. Found amongst conferva. Length 

 l-900th to l-120th. 



112,, CLOSTERIUM? cylindrus. The cylinder- shaped 

 Closterium. Lorica ovato-cylindrical ; scarcely three times 

 as long as broad, slightly constricted at the middle, and 

 very obtuse at both extremities. Marked exteriorly with 

 granulated radiations of the shell. Length 1 -430th. 



113. CLOSTERIUM margaritaceum. The pearly Clos- 

 terium. 'Lorica straight, cylindrical, and elongated, eight 

 or nine times as long as broad, and slightly constricted at 

 the middle, rounded at both extremities, and marked 

 exteriorly with strings of pearl-like granules; moveable 

 points at some distance from the extremity. Length 

 l-240th to l-200th. 



