288 University of California Puhlications in Zoology. [Vol.8 



basis is most nearly related to Peridi)iium. In reaching this 

 conclusion he was evidently influenced by the presence of a 

 narrow midventral plate in the epitheca, apical 1' of my nomen- 

 clature (pi. 18, fig. 2) and r of his (pi. 18, fig. 6), the homologue 

 of the rhomb plate of Peridinium, and by the fact that the total 

 luimber of plates in both his form and in Peridinium was appar- 

 ently the same. Although he explicitly notes the general re- 

 semblance of the hypotheca to that of Gonyaulax he still con- 

 cludes that "sowohl nach der Gestalt der Schale wie audi der 

 Z usammc nsetzung derselben aus Tafelu schliesst unsere Art am 

 meisten an die Gattung Peridinium an, in welche ich sie audi 

 deshalb angereiht habe." 



The diagrams of the plates of his Peridinium eatenatum in 

 an apical view of the epitheca and a view of the hypotheca from 

 above looking toward the antapex are reproduced in plate IS. 

 figures 6 and 7. The results of my analysis are shown in 

 figures 1 and 2. The numbers and general relations of the 

 plates in the epitheca are essentially similar in his diagram and 

 my own, the differences being mainly in the relative dimensions 

 of the plates and directions of the bounding sutures portrayed 

 in the two diagrams. 



In the analysis of the hypotheca, how^ever, there are two 

 differences between the two diagrams (figs. 2 and 7) which have 

 an important bearing on the relationships of the species in ques- 

 tion. Levander figures the hypotheca as composed of six post- 

 cingular plates (his "post-aquatorialen Felder" I, I'-V), a mid- 

 ventral furrow plate, and a pentagonal antapical plate which 

 in his figure is deeply invaded by an elliptical area (unlabeled) 

 hearing the posterior point of connection with the adjacent mem- 

 ber of the chain. As determined by me the hypotheca (pi. 18, fig. 

 1 ) consists of six postcingular l'"-6'" one posterior intercalary 

 1^' one antapical 1"". and the ventral area composed of several 

 intermediate plates {int. pi.) and a widely expanded posterior 

 plate (post, pi.) bearing the posterior attachment pore (post. 

 att. po.) . This plate is not deeply indented into the antapical. 

 The hypotheca as thus analysed corresponds plate for plate with 

 that of Gonyaula.c, not of Peridinium. 



