EXPLANATION OF PLATE XXVII. 



-Lateral view of lorica of Cyttarocylis quadridens, X250. 



-Lateral view of posterior ends of loriea of C. quadridi n.t, showing 

 asymmetry and degrees in development of the lateral spines, 

 X250. 



-Lateral view of posterior end of lorica of C. quadridens, showing 

 lumen, X1200. 



-Optical section of wall of loriea of C. quadridens, Bhowing pris- 

 matic elements, X1200. 



-Optical section through posterior end of lorica of Cyttarocylis 

 torta, showing lumen, X600. 



-Anterior end of loriea of C. torta, viewed as a transparency. Lo- 

 rica with additional posterior ring, X320. 



-Posterior end of lorica of C. torta, showing 90° of torsion, X600. 



-Another lorica of the same, showing 180°, X600. 



ABBREVIATIONS. 



ana. — angles of quadrangular pedicel. 

 exp.— expansion nf pedicel. 

 J.— lumen of lorica. 

 o. ap. — oral aperture. 

 [>, d. — pedicel. 



pr. el. — prismatic elements. 



quadrangular expansion of 

 lorica. 

 t. s. — terminal spine. 



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