1920] Kofoid: New Interpretation of the Structure of Noctiluca 319 



ably extends the body along its axis. The groove just above the 

 tentacle (4) sinks rather deeply into the body, forming a recess, the 

 oral pouch. At one side of this at some distance from the tentacle 

 arises (5) a threadlike flagellum which almost reaches the base of the 

 tentacle with its free end. At one side, and slightly in advance of the 

 origin of this flagellum there is (6) a membranous or somewhat pro- 

 longed and ribbonlike projection called by Huxley (1855) the tooth. 



_ post. p. 



long. fl. 



Fig. A. Typical dinoflagellate, Gyrodinium corallinwm, gen. nov., sp. nov., 

 Kofoid and Swezy MSS, showing sulcus, girdle, and two flagella. x 500. Ant. p., 

 anterior pore; epi., epicone; git., girdle; hyp., hypocone; interc. a., intercingular 

 area; long, fl., longitudinal flagellum; n. nucleus; pig., pigment; post, p., posterior 

 pore; pus., pusule; sulc, sulcus; tr. fl., transverse flagellum. 



Close to this and at one side of it there appears, especially in the 

 smaller and presumably younger individuals, (7) a shallow trough, 

 the girdle, hitherto unnoted, which branches off from the main groove 

 in a short arching curve which speedily dies out on the rotund side 

 of the body. Adjacent to the deep pit above the tentacle is gathered 

 the denser, granular mass of the cytoplasm, enclosing the nucleus, and 

 from it radiate the anastomosing strands of cytoplasm passing to the 

 outer pellicle of the body. 



The fundamental organs upon which are based the structure of the 

 Dinoflagellata are the girdle and the sulcus (fig. A, gir. and side). 



