EXPLANATION OP PLATE XXVIII. 



Fig. 16. — Lateral view of loriea of Cyttarocylis torta, having no additional 

 ring, X250. 



Pig. 17.— Optical section and inner surface of anterior end of loriea of 

 C. torta, showing prismatic structure, X375. 



Fig. .a.— Surface of loriea of C. quadridens, showing primary and second- 

 ary reticulations, X1100. 



Fig. 19.— Lateral view of loriea of Cyttarocylis pulchra, having three 

 rings, X250. 



Fig. 20. — Optical section and inner surface of loriea of C. pulchra, showing 

 prismatic structure, X500. 



Pig. 21. — Posterior end of loriea of C. pulchra, X500. 



Fig. 22. — Optical section of same, showing lumen, X500. 



Fig. 23. — Anterior end of loriea of C. pulchra, viewed as a transparency. 

 Loriea with modified central ring, X250. 



ABBEEVIATIONS. 



o. a p. — oral aperture. 



ped. — pedicel. 



pr. eh— prismatic elements. 



pr. ret.— primary reticulation. 



qu. ex. — quadrangular expansion. 



)'.— rings. 



t. s. — terminal spine. 



sec. ret. — secondary reticulation. 



