291 



7. The Structure and Systematic Position of Polykrikos Biitsch, 



By Charles Atwood Kofoid, Zoological Laboratory, University of California. 



(With 1 figure.) 



eingeg. 28. November 1906. 



The infusorian described by Ouljanin (1868) ^ as a Tiirbellarian 

 larva, by Biitsch li (1873)2 as the infusorian Polijhrikos, and again by 

 Bergh (1881)3 ^g one of the so-called Cilioflagellates, has presented 

 certain structural peculiarities which have isolated it, rendered its 

 position in classification uncertain and obscured its relationships. 

 Biitschli in his »Tierreich« monograph places it in the family Poiy- 

 dinida of the suborder Dinifera of the Dino flagellata. Calkins raises 

 the group Polydinida to the ordinal rank coordinate with the Diniferida. 

 Schutt in his Plankton-Expedition Report makes no mention of it and 

 omits the genus entirely from his »Pcridiniales« of the »Pflanzenfamilien« 

 of Engler and Prantl. 



An abundance of material, apparently of the European species, has 

 enabled me to make a reexamination of the animal at the San Diego 

 Station where it occurred in large numbers in the neritic surface plank- 

 ton during the past summer. 



Instead of having only a single longitudinal flagellum, with j)Ossibly 

 a secondary accessory one (P. schwartxi Biitschli) for the 4 — 8 transverse 

 ones as hitherto described, there is always present a longitudinal fla- 

 gellum for every transverse one. The slightly oblique longitudinal furrow 

 is in reality a series of furrows joined end to end and the animal is ac- 

 cordingly a colony of four or eight individuals en chaine, each with its 

 transverse and longitudinal furrow and their corresj)onding flagella. 

 These flagella, as in some other D ino flagellata ., have their origin in 

 separate pores placed near each other, that of the transverse flagellum 

 being at the junction of the longitudinal and transverse furrows and that 

 of the longitudinal flagellum lying in the longitudinal furrow a short 

 distance behind the other j^ore. The two flagella present the characte- 

 ristic differences seen in other Bino flagellata. The transverse one in life 

 exhibits intermittent spiral motion jirogressing distally on the lash, and 

 when not in motion retains its spiral form. In preserved material (for- 

 malin) it is sinuous with ragged margins. The longitudinal flagella on the 

 other hand exhibit wave-like undulations of wider amplitude which 



1 Ouljanin, Protokolle d. K. Gesellsch. d. Freunde d. Naturwiss. zu Moskau. 

 1868. S. 61, fide Leuckarts Jahresb. 1868—1869. S. 123. 



2 Biitschli, 0., Einiges über Infusorien. Arch. f. mikr. Anat. Bd. 9. S. 657 

 —678, Taf. 27. 



3 Bergh, R. S., Der Organismus der Cilioflagellaten. Morph. Jahrb. Bd. 7. 

 S. 177-288, Taf. 12—16. 



