26 University of California Publications in Zoology [Vol. 11 



Girdle slightly posteqiiatorial, descending, displaced distally 

 less than a girdle width, if at all, scarcely indented, without lists 

 or prominent ridges or ribs. Epitheca hemispherical, a trifle 

 larger than hypotheca. No apical region differentiated. 



The ventral area foreshortened, triangular, widening an- 

 teriorly to 0.3 transdiameter. Its total length is little more than 

 a transdiameter. It is curved slightly towards the left of the 

 body posteriorly, not deeply impressed, and without heavy ridges 

 or lists. 



Apical plates three, the midventral 1' wider than long in ven- 

 tral view, pentagonal, meeting 2' and 3' at the point homologous 

 to the apex of Gonyaulax at a point about 30° ventral to the 

 apical pole. Posteriorly apical 1' meets the anterior plate {ant. 

 pi.) of the ventral area, and thus parts precingulars 1" and 6". 

 Dorsal apicals 2' and 3' are large plates uniting with a third 

 somewhat larger plate 1", the anterior intercalary, a little dorsal 

 to the apical pole of the skeleton. This relationship has led 

 Lemmermann (1907) to designate these three as apical plates. 



The six precingulars l"-6" are subequal, except 1", which is 

 somewhat smaller, and 3", which is larger than the others. 



The girdle plates 1-6 have the same arrangement as in 

 Gonyaulax. The much widened ventral area provides anteriorly 

 for the admission of one of its intermediate plates into the prox- 

 imal end of the girdle adjacent to the flagellar pore. It, as well 

 as another plate of the group, has in this species by virtue of 

 position and prominence a claim to be considered as belonging to 

 the girdle series, but comparison with conditions as found by me 

 (1911a, 1911b) in various species of Gonyaulax and in Spiraula.z 

 lead to the conclusion that the six plates 1-6 are the homologues 

 of the girdle plates in these genera and that the other two belong 

 to the intermediate group of the ventral area. 



There is no posterior intercalary plate. Both postcingular 

 1' " and the antapical 1" " are comparatively large in this species 

 and it seems probable that the former includes the surface usually 

 occupied by the posterior intercalary plate in related genera. 

 The hexagonal antapical is not indented by the ventral area. 



The ventral area is peculiar in this species in that its anterior 

 part spreads laterally at the girdle, attaining a width of 0.3 



