804 



PERIDINEAE OF NEW SOUTH WALES, 



dimensions and general characteristics. The arrangement of the 

 plates in the epivalve also is on much the same lines in both, 

 and there is a similarity in their disposition in the hypovalve. 

 Yet on the other hand there are distinct differences which are 

 constant, no intermediate forms have been noted, and there is a 

 series of well-marked varieties connected with each species. The 

 fundamental character of the species is (in dorsal view) the 4th 

 equatorial and two dorsal apical plates meeting at a point (or 

 nearly so) below the apex. This point in the type is about 

 two-fifths of the altitude of the epivalve from the tip. 



Var. elegans, n.var. (Text-fig. 10). 



Forma valde ovata, modo angulata. Epivalva conica, fere 



triangularis, sursum acuminata; fovea apicali instructa; lateribus 



symmetricis quam levissime arcuatis, fere rectis, paullulo angu- 



latis; tabulis sequatoriis prae epivalva? altitudinem altissimis; 



tabula rhomboidea sursum plus minus arcuata . Hypovalva tabu- 



Text-fig.lO. Text.fig.ll. 



Peridinium geminum Peridinium geminum 



var. elegans, n. var. var. excavatum , n. var. 

 (x 1000). (x 1200). 



lis antapicalibus aequalibus. Cetera ut in forma typica. 



Long. 25-26, lat. 21-23, epiv. alt. 14J-16 p. 



Guildford (70) ; Sydney Water Supply (100) . 



A very elegant form, quite symmetrical and markedly ovate, 

 slightly faceted. The transverse furrow, as in the type, very 



