330 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA 



Description. — The body is asymmetrical ellipsoidal, broadest in the middle and rounded at 

 the apices, its length 1.5 transdiameters at the widest part. The hypocone exceeds the epicone 

 in size, its length being greater by 0.22. The epicone is broad and rounded with a length on the 

 left and right sides of 0.19 and 0.53 of the total length of the body. It slopes obliquely to the 

 right. The hypocone is rounded on the right side with the antapex and left side sloping 

 obliquely towards the girdle on the left side. 



The girdle begins near the anterior end of the body at a distance from the apex of 0.19 of 

 the total length of the body. It follows a descending left spiral course around the body, dis- 

 placed posteriorly on the right side about 0.3 transdiameter. The furrow is wide, about 0.18 

 transdiameter, and is deeply impressed with overhanging borders. The sulcus extends from the 

 girdle to the posterior end, but is omitted from Schilling's (1891ct. 1913) figures. The transverse 

 flagellum traverses the entire length of the girdle. The longitudinal flagellum arises near the 

 distal end of the girdle. 



Nucleus and pusules are not figured for this species. The peripheral zone of cytopla.sm is 

 filled with large, round, disklike, light yellow chromatophores. A carmine-colored stigma is 

 present in the sulcal region below the insertion of the longitudinal flagellum. 



Di:m:exsioxs. — Length, 23m; trausdiaraeter, 18.4/^ is given by Schilling 

 (lS91rO in the text, bnt his figures have a width of about 15/^. This dimension 

 has been used in the above description. 



OcciTERExcE. — Figiired by Schilling (1891a) from the swamps in the neigh- 

 borhood of Basel, Switzerland. The only other record of its occurrence is that 

 by Massart (1901) in brackish ditches around Palingbrug, Belgium. 



Syxoxymy. — Originally described by Schilling as Gymnodinium pusillum 

 and later transferred by Lenunermann (1899, 1903) to Spirodinium, an allo- 

 cation followed by Schilling in his monograph of German fresh-water dino- 

 flagellates (1913)." 



CoMPARisoxs. — This species, with G. ]nj(dh)U)n, are the only representatives 

 of Gyrodinium thtis far described from fresh water. It is also one of the four 

 species of the genus with chromatophores. It greatly resembles G. hycdinum, 

 differing from it mainly in the possession of chromatophores. 



Gyrodinium rubricaudatum sp. nov. 



Plate 10, figure 116; text figure DD, 18 



DiAGXOSis. — A medium sized species with s;\^nmetrically ellipsoidal to 

 biconical body, its length 2.16 transdiameters, girdle submedian, a descending 

 left spiral displaced 0.44 transdiameter ; sulcus extends from near apex to near 

 antapex : surface with broken striae ; color, greenish yellow with coral-red pig- 

 ment. Length, 93/^. Pacific off La Jolla, California, July, August. 



Description. — The body is symmetrically ellipsoidal, approaching biconical, in outline, cir- 

 cular in cross-section, tapering towards both apices, its length 2.16 transdiameters at the widest 

 part. The hypocone is slightly larger than the epicone in size, its length being greater by 0.08 

 of its own length. The epicone is convex-conical (50°) in outline with narrow, blunt apex. It 

 has a length on the left and right sides of 0.36 and 0.58 respectivelj' of the total length of the 

 body. The hypocone has a slightly greater transdiameter and its sides are more convex than 

 those of tlie epicone. The posterior end is prolonged into a short club-shaped projection at the 

 antapex. The length of the hypocone on the left and right sides is about 0.62 and 0.45 respec- 

 tively of the total length of the body. 



