404 ilEMOIRS OF THE UNIVERSITY OF CALIFORNIA 



Historical Discussiox 



The possession of a stout mobile tentacle affords an adequate justification 

 for geneiic distinction of organisms from those without this characteristic. 

 Indeed, the possession of this organ in Xoctihica was one of the prime grounds 

 for the establishment of the order Cystoflagellata. The genus differs from 

 Protodinifey in the presence of a complete girdle not posteriorly located. l)ut 

 resembles it strikingly in the shajje, location, and behavior of the tentacle. It 

 differs from ErjjfJiropsis in having a girdle of the slightly displaced Gtjro- 

 diiHum type and in the entire absence of the eyespot, although the presence of 

 the brilliant brown pigment in the tentacle is suggestive of the ingmentation 

 in that genus. It differs from Noctiluca in the completeness of the girdle and 

 in having the typical form of the G^^nnodiniidae instead of that of the inflated, 

 subspherical body of XoctUuca. 



The genus is named in honor of Professor J. Pavillard. the botanist of 

 JSrontpellier, whose researches at the Station Biologique at Cette, France, have 

 added much to our critical knowledge of the Diuoflagellata. 



Pavillardia tentaculifera sp. nov. 



Plate 10, figure 114: text figure JJ 



DiAGxosis. — A medium sized species with stout ovate body, its length 1.75 

 transdiameters ; girdle slightly premedian, displaced 0.33 transdiameter : sulcus 

 extending from near apex to antapex ; surface faintly striate ; stout club-shaped 

 tentacle directed posteriorly from antapex; color, pale yellow. Length, 58?^. 

 Pacific off La Jolla, California, July. 



Description. — The body is stout ovate, widest posteriorly ; circular in cross-section, its length 

 1.75 transdiameters at the widest part. The hypocone exceeds the epieone in size, its length 

 being greater by 0.16. The epieone is acorn-shaped with minute, acute apical point at the apex. 

 It has a length on the left and right sides of the body of about 0.38 and 0.5 respectively of the 

 total length of the body. The hypocone has a length of about 1.3 transdiameters, expanding 

 midway to about 1.16 transdiameters in width. The antapex is low conical with a club-shaped 

 tentacle extending posteroventrally from its tip. 



The girdle is complete, forming a descending left spiral abruptly curved posteriori}' at its 

 distal 0.15 to a total displacement of 0.35 transdiameter. The furrow is deeply impressed with 

 slightly protuberant lips, with the anterior shelf undercut and the posterior sigmoid in optical 

 section. Its width for most of its course is about 0.05 transdiameter and in the distal 0.15 this 

 is reduced to a very narrow cleft which, however, completes the circuit. The transverse flagellum 

 does not reach beyond 0.75 of the circuit. It is a fine ribbon thrown into minute iindulations 

 traveling distally along its length. The pore for the transverse flagellum lies at the proximal 

 end of the girdle. 



The sulcus lies on the flattened ventral face and extends from within a short distance of the 

 apex posteriorly in a straight line to the proximal end of the girdle and thence with a sweeping 

 curve to the left posteriorly to the antapex, ending at the junction with the tentacle. No pore 

 for a longitudinal flagellum was detected. Apparently in lieu of the usual threadlike posterior 

 or longitiulinal flagellum this species in common with Protodinifer tcnta^'ulafum has a stout 

 tentacle-like prolongation on the posterior end of the body and ventral furrow. This tentacle 



