KOFOID AND SWEZY: UNARMORED DINOPLAGELLATA 115 



woTild lead to the higher Diniferidae. It forms a connecting link between the 

 Adiniferidea and the Diuiferidea and supports the monophyletic origin of the 

 Dinoflagellata. 



'a*- 



Protodinifer marinum (Lohmann) Kofoid and Swezy 



Ehynchomanas marina Lohmann (1902), pp. 7, 48, pi. 2, figs. 42-45; (1909), p. 223, fig. 4, 



nos. 36, 37. 

 R. marina, Liihe (1913), p. 261, fig. 266. 



DiAGXosis. — Elongate fusiform or i:)yriform, length 2.6 diameters, tentacle 

 slender, 0.25 length of body in length ; length, 12— 40m. Marine. 



Description .—Lohmann (1902) gives a brief description and a few incomplete figures which 

 afford the basis for the following account. Body fusiform in free state, length 2.1-2.6 times 

 greatest diameter which may be equatorial or in the pasterior third of the body. A tendency to 

 become pyriform and enlarged posteriori}' is seen in the smaller individual and in encysted and 

 contracted stages. No trace of a girdle was figured or recorded. The slender tentacle is in all 

 cases figured as terminal and no sulcus is clearly shown. Only a single posteriorly directed 

 flagellum is figured. This is nearly 1.4 the length of the body in length. In the so-called young 

 stage the tentacle is figured as stout, much like that in P. tentaculatum. No nucleus is described, 

 but a spheroidal yellow body quite similar to that in P. tentaculatum is located posteriorly. A 

 few large refractive spherules occur in the rounded antapical region and a cluster of smaller 

 refractive corpuscles lie anterior to the yellow body. A flask-shaped pusule is found near the 

 anterior end of the body. 



Encystmeut occurs with the formation of a thin, closely adherent membrane from which the 

 tentacle protrudes. The cyst later expands into a sphere and the body takes on a stout pjT-iform 

 shape within it. 



Dimensions. — Length, 12 to 40/^ ; greatest diameter, 5 to 17^ ; tentacle, 2 to 10m. 



Occurrence. — Reported by Lohmann (1902) from the plankton in the Bay 

 of Kiel and later in 1909 in the food contents of the digestive tract of Appendi- 

 culnria from the Baltic and Mediterranean seas, but not explicitly from the 

 latter. 



Comparisons. — This species differs from P. tentaculatum mainly in size. 

 It ranges from 12 to 40m, while the specimens of the former species are 54m in 

 length. The tentacle also appears to be more slender and to be terminal, but 

 Lohmann 's figures ma}' not be critical on this point. It also has a body of a 

 more slender type and a longer transverse flagellum. Lohmann does not figure 

 the minute longitudinal flagellum if there be one. The resemlilauce to Proto- 

 dinifer is so striking that we are led to transfer the species from Rhynchomonas, 

 where Lohmann placed it, to Protodinifer in the face of the facts that that 

 author did not note any trace of a girdle, any longitudinal flagellum, or any 

 nucleus. This may prove to be of the dinoflagellate type with beaded chro- 

 matin. "We saw no individuals of P. tentaculatum with the very slender tentacle 

 which Lohmann figures for this species. The two species are close together 

 and may prove to be identical. However, with our present knowledge, the 

 differences in size, tentacle, and flagellum are such as to lead to specific 

 separation. 



