462 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA 



described and figured. Pavillard (1905) records P. rosea as rare in the plank- 

 ton of tlie Etang de Thau at Cette, France, on the Mediterranean in October. 

 1904. Surface temperatiu'es during tliis month ranged from 18 -l C to 13-9 C. 



The only records which can be considered as possibly including P. rosea, as 

 here delimited, are those of Paulsen (1907) and Ostenfeld (1913) which refer 

 to specimens seen by the latter in plankton from the Xorth Sea off Tyborn, 

 Denmark, in March and April, 1900, and from the Cattegat in May, 1898. Their 

 status is, however, not critically determinable. 



CoMPARiso]srs. — This is the only species in the genus Pouchetia with a red 

 pigment mass instead of the usual black melanosome. The relatively slight 

 torsion of the body, about 0.25 turn, the red instead of black pigment and 

 elongate laminate lens indicate that this is one of the simpler species of the 

 subgenus Pouch efiella. 



The differences between the figiires of Pouchet (1887) and Pavillard (1905) 

 are considerable. Pouchet 's has a length of 44m, Pavillard 's of 58m. The former 

 is 1.66 transdiameters, the latter 1.3 in length. The lens expands distally in 

 the former and does not in the latter; the former is somewhat angular, the 

 latter rotimd. These differences are possibly referable to the fact that 

 Pouchet 's specimen was not encysted while Pavillard 's was in a cyst and ap- 

 parently well rounded up. The upper one of Pouchet 's figures (both are turned 

 upside dowTi) has an expanded truncate postmargin. This suggests that it had 

 recently disgorged a food ball such as is seen in the lower figure (compare our 

 fig. 61, pi. 6) of Pouchetia maxima, which has a similar antapical margin and 

 had recently discharged a food mass. 



Syxoxymy. — Originally described by Pouchet (1887) as Gi/»niodininm 

 pohjphemus var. roscum, but transferred to Pouchetia by Schiitt (1895), who 

 a^Dplied the name to an assemldage of at least two species different from 

 Pouchet 's. The synonymy of this species is full of perplexities arising from 

 the inadequacy of Pouchet 's (1887) original account and figures, from his re- 

 lating of his form to his G. poli/pheuius as a variety, and from Schiitt 's allo- 

 cation in Pouchetia rosea (Pouchet) of what appear to us to be two distinct 

 species, neither of which is referable in our opinion to Pouchet 's original P. 

 roseum. There is also, at present, lack of adequate and critical knowledge of 

 the limits of variability within the species of this group and of the pathological 

 changes which the constituent parts of the ocellus may undergo. It is also 

 possible that encystment may modify the condition and appearance of the ocellus. 



In view, however, of the structural features involved in speciation in this 

 genus as a whole we have arrived at the following tentative solution of the 

 perplexities surrounding this species: 



1. Pouchet's Gyimiodinium poJijphcmus var. roseum (1887) is a distinct 

 species, Pouchetia rosea (Pouchet), but not P. rosea (Pouchet) Schiitt or 

 Gymnodinium roseum Dogiel or G. roseum Lohmann. It is not Pouchet's 

 G. pohjphemus (ISSoh). 



