146 The Mastigophora 



Fig. 4. 22. AD. DiuospJmera palustris, ventral, dorsal, apical, and anta- 

 pical views; x575 approx. (after Eddy). E-H. Chalubinskia tatrica Wolo- 

 szynska, ventral, left lateral, apical, and antapical views; x675 (after W.). 

 I-K. Peridiniufn kulczynskii Wolosz)nska, \entral, apical, and antapical 

 views; x835 (after W.). L. Amphidiniopsis kofoidi Woloszynska, ventral view; 

 x630 (after W.). M-O. Glenodiniopsis steinii W'olos/ynska, ventral view; 

 x850 (after W.). P, Q. Sphaerodinium limneticuui Woloszynska, x800 ap- 

 prox. (after W.). R. Staszicella dinobryonis Woloszynska, x720 (after W.). 



Sphaerodinium Woloszynska (Fig. 4. 22, P, Q), and Staszicella AVoloszynska (Fig. 4. 22, 

 R). Tfie epitheca is distinctly smaller than the hypotheca in Amphidiniopsis and 

 Staszicella. The two genera are distinguished by the sulcus, which extends to the apex 

 in Amphidiniopsis, but only a short distance into the epitheca in Staszicella. 



Family 4. Ceratiidae. The epitheca is prolonged into an apical horn, 

 the hypotheca into two or three posterior horns (Fig. 4. 23, A). The genus 

 Ceratium Schrank is represented by many marine and several fresh-water 

 species (74, 80). Species differ in number of posterior horns, in form and 

 length of the horns, and in the sculpturing and detailed pattern of the 

 thecal plates. Of the posterior horns, the accessory may be vestigial or 



