94 University of California Puhlications in Zoology [Vol. 18 



A second feature of the relations of this girdle to the organization 

 of the dinoflagellates is the fact that the point of contact of anterior 

 and posterior schizonts in chain formation, or at binary fission, is at 

 the distal end of the girdle of the anterior cell and the apex of the 

 posterior one (figs. 7, 8). The apical pore at the anterior tip of the 

 posterior daughter cell is thus in direct protoplasmic continuity with 

 the anterior cell at the distal end of the girdle. Its shaft lies in a 

 channel below the girdle and its tip is thrust against the anterior 

 shelf or lip of the girdle. When the schizonts part, this depression 

 persists for some time as an attachment area {att. ar., fig. 5) but may 

 ultimately fade away. It appears that Faure-Fremiet (1914) has 

 interpreted this attachment area, or a region near it, at the distal end 

 of the girdle as the flagellar pore of its proximal end in Erythropsis. 

 The apical horn of Ceratium is modified to fit the attachment area 

 (fig. 7) and this modification persists for some time after the detach- 

 ment of the schizonts. The apex of Erythropsis is homologous to this 

 apical pore of Ceratium and may be expected to detach from the 

 attachment area at binary fission, as well as to undergo some readjust- 

 ment after detachment. 



The relationships of two schizonts in chain in Cochlodinium citron 

 are shown in figure 8. In case of the reversal of symmetry and orien- 

 tation proposed by Faure-Fremiet (1914) for Erythropsis, the adjust- 

 ments necessitated in chain formation would be considerable. The 

 proposed orientation provides neither attachment area nor apical 

 point. 



It has not infrequently been the fate of rare and at the same time 

 peculiar or novel organisms to be strangely or even absurdly misinter- 

 preted. Thus Nitzsch (1817) described a Ceratium as a Cercaria and 

 Uljanin (1870) interpreted Polykrikos as a Turbellarian, and the larva 

 of the Syrphid fly Microdon was described as a mollusk. 



Such misfortune has attended few organisms so persistently as it 

 has the ill-starred Erythropsis, a unique genus of the Dinoflagellata, 

 in which there has developed a remarkable stigma or ocellus with amoe- 

 boid melanosome, hyaline laminate lens, and pigmented sensory (?) 

 core or end organ, as well as a highly specialized, remarkablj' active, 

 protrusible and retractile prod (tentacle, Hertwig (1884), dart, Faure- 

 Fremiet (1914)), directed posteriorly from a ventro-posterior recess 

 (figs. 11, 12). 



Up to the time of Faure-Fremiet 's observation (1914) only six 

 individuals of the remarkable genus had been reported. In most, if 



