22 University of California Publications in Zoology [Vol. 11 



The differences between Lemmermann 's analysis and our own 

 are of two kinds : first, those resulting from a different interpre- 

 tation and allocation of certain plates; and second, those result- 

 ing from an extension of the analysis to the plates in the girdle 

 and ventral area. A comparison of Lemmermann 's interpreta- 

 tion and our own will be facilitated by reference to his figui'es 

 here reproduced (figs. 1-5), and those (figs. 6-8) giving our own 

 analysis. 



The differences between Lemmermann 's analysis and our own 

 of the epitheea are wholly those of interpretation and allocation. 

 In the genera Gonyaulax and Peridinium the "Rautenplatte" or 

 apical 1' of my nomenclature, is the midventral plate of the apical 

 series and is normally in contact with the so-called apical pore. 

 In Dinosphaera there is no apical pore and apical 1' is much fore- 

 shortened and the dorsal intercalary 1" correspondingly enlarged, 

 so that the structural apex {ap., fig. 6) or region where the apicals 

 converge is pushed over upon the ventral face and the point of 

 convergence of the anterior intercalary 1" and the two dorsal 

 apicals 2' and 3' occupies the functional apex of the skeleton. 

 Lemmermann calls the anterior intercalary an apical and desig- 

 nates the ventral apical as the "Rautenplatte." 



The girdle plates, 1-6, are six in number, as in Gonyaulax, a 

 short plate at the proximal junction of girdle and ventral area 

 {int. pi.) being regarded as belonging to the ventral area. Lem- 

 mermann figures three of the girdle sutures, but does not other- 

 wise specify the number of the girdle plates. 



The hypotheca of Gonyaulax is uniformly composed of six 

 postcingulars, one posterior intercalary, and one antapical. Lem- 

 mei'mann states that there are five " Postequatorialplatten, " one 

 accessory plate, and one antapical. Since the additional post- 

 cingular in Gonyaulax discovered by me (1911a) is always a 

 minute plate formerly overlooked, it seemed to me probable that 

 it would be found in G. palustris. This expectation, combined 

 with Lemmermann 's (1907) statement that an accessory plate 

 occurred in the hypotheca, led me (1911a) to retain G. palustris 

 in the genus Gonyaulax. Our examination of the skeleton, how- 

 ever, fails, with the closest scrutiny, to reveal the least trace of 

 the homologue of the minute postcingular 1' " of Gonyaulax. 



