430 University of California Puhlications in Zoology [Vol. IS 



Metaperidinium. — Under Metaperidinium, which may be called 

 Metaperidinium (dextrad) for those species in which the growth of 

 the girdle plates has proceeded unequally and more rapidly on the 

 right side of the organism than on its left, we find combinations with 

 both of the sjonmetrical dorsal patterns, primary and secondary, and 

 also a combination of this ventral pattern with the asymmetrical 

 dorsal pattern of fig. 7, which may be designated as constituting the 

 group of Metaperidinium (dextrad), dorsally right oblique. 



Under the group of Metaperidinium (dextrad) primary, we find 

 the following species : 



P. divergens Ehrbg. P. globulus Stein 



(Stein, 1883, pi. 10, fig. 2; (Broch, 1910, p. 182, fig. 2, II) 



supported by numerous ob- P. monacanihus Broch 

 servations of the writer) (Broch, 1910, p. 150, fig. 25) 



P. adriaticum Broch P. brevipes Pauls. 



(Broch, 1910, p. 192, fig. 8, II (Paulsen, 1911, p. 313, fig. 13) 



and III; probably a variety P. breve, Pauls, 

 of P. divergens) (Broch, 1910, p. 47, fig. 21) 



P. crassipes Kofoid forma typica P. wicsneri Schiller 



Broch (Schiller, 1911, p. 2, fig. 2) 



(Broch, 1910, p. 53, fig. 27) P. lenticuJatum F. F. 

 (Broch, 1910, p. 194, fig. 9) (Faure-Fremiet, 1908, p. 217, 



P. crassipes, forma autumnalis fig- 4) 



Broch P. curvipes Ost. 

 (Broch, 1910, fig. 10, III) (Broch, 1910, p. 43, figs. 10, 



P. quarnerense (Schroder) Broch 12, and 13) 



(Broch, 1910, p. 184, fig. 3) (Pavillard, 1916, p. 35, fig. 8) 



Only one reliable instance of the occurrence of the secondary 

 dorsal plate pattern in Metaperidinium is at hand. P. roseum Pauls. 

 (Paulsen, 1904, p. 23, fig. 9). 



Specimens showing an unequal development of the end plates of 

 the precingular row but in a reverse order from that found in Meta- 

 peridinium (dextrad), and hence to be held for the group which may 

 be known as Metaperidinium (sinistrad) if represented, are as yet 

 unknoMai, if we may except a doubtful figure by Claparede and Lach- 

 mann. 



At least two cases are reported of the combination of the ventral 

 plate pattern of Metaperidinium (dextrad) with an asymmetrical 

 dorsal pattern, that which we have termed the dorsally right oblique 

 pattern, shown in fig. 7. These are : 



P. mite Pav. P. sieinii Joerg. 



(Pavillard, 1916, p. 37, fig. 9) (Kofoid, 1909, pi. 2, figs. 1, 5, 



and 7) 

 (Broch, 1910, p. 185, fig. 4) 



