42 MEMOIRS OP THE UNIVERSITY OF CALIFORNIA 



In the tribe Periclinioiclae, as in the Proroeentridae, the surface is still 

 further elaborated by the development of a theca of discrete plates, often of a 

 perfection of form and finish and of a beauty of design surpassed by no other 

 similar group of structures. This exoskeleton exhibits a tendency to show longi- 

 tudinal linear marldngs not unlike the linear striae of the periplast of the un- 

 armored dinofiagellates in niunber, location, and distribution. 



