1920] Kofoid: New Interpretation of thi Structurt of NoctUuca 329 



vacuoles. It retains the sulcus, modified anteriorly into the apical 

 trough, but only the proximal part of the girdle persists. "With the 

 degeneration of the girdle the transverse flagellum is reduced to the 

 prehensile tooth. The posterior tentacle is the homologue of the 

 tentacle of Pavillardia and Erythropsis and is not a modified flagellum. 



Relationships op NoctUuca and Status of the Cystoflagellata 



The order Cystoflagellata was established by Haeckel (1873) to re- 

 ceive NoctUuca whose aberrant structure seemed to detach it from other 

 flagellates. Later the genera Leptodiscus Hertwig (1878), Craspedo- 

 tella Kofoid (1905) and Radiozoum Mingazzini (1904) were added. 

 The last named is undoubtedly a skeletonless radiolarian allied to 

 Globicella Borgert (1907). Leptodiscus and Graspedotella are so little 

 known that the decision as to their final affinities may well await 

 further investigation. They may equally well be left, pending new 

 data on their relationships, as an undistributed residue in the thus 

 emended "Cystoflagellata," whose nomenclatural status is imperilled 

 by the removal therefrom of its type genus NoctUuca. 



The evidence adduced in this paper establishes the affinities of 

 NoctUuca to the Dinoflagellata and to the tribe Gymnodinioidae, since 

 NoctUuca has in common with this tribe the girdle and sulcus and the 

 two flagella and lacks a theca or cuirass. 



In view of the high specialization induced by hydrostatic inflation 

 and of the presence of the tentacle it seems justifiable to utilize in the 

 Gymnodinioidae the family Noetilucidae Saville-Kent for the genus 

 NoctUuca and the other tentaculate non-ocellate genus Pavillardia 

 Kofoid and Swezy MSS. 



There appears thus to be no adequate morphological justification 

 for the separate order of Protozoa for the reception of NoctUuca, such 

 as Haeckel (1873) created in his Cystoflagellata. This order can only 

 be maintained in emended form to exclude NoctUuca and retain 

 Leptodiscus and Craspedotella tentatively. 



Summary 



1. NoctUuca is a tentacle-bearing dinoflagellate with a sulcus, girdle, 

 and longitudinal and transverse flagella. 



2. The sulcus is longitudinal and midventral. It includes the 

 apical trough and the recessed oral pouch and cytostome. 



3. The tentacle arises from its posterior end. 



