KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 117 



Herouard (1896) assigned it to the Heteromastigina and Senn (1900), in his 

 earlier monograph of the flagellates, placed it in the Bodonaceae. Poche (1913) 

 does not allocate it in his "System der Protozoa." 



The gronnds upon which Oxyrrliis may be considered a primitive dinofla- 

 gellate are its imperfect girdle and its apparent lack of differentiation of the 

 transverse flagellum into the typical ribbon. The sulcus appears to be incom- 

 pletely differentiated. The tentacidar lolie, however, is a specialized rather 

 than a primitive feature. It appears to be homologous with the tentacle of 

 Protodinifer. 



The fact that the thecate genus Prorocentrum, of the Adiniferidea also has 

 a projection near the flagellar pore is significant, especially if this group is an 

 offvslioot from lower Diniferidea of which Protodinifer and Oxijrrhis are the 

 existing representatives. The fact that the tentacle in these two genera is a 

 mobile organ and the projection of Proroeoitrum, an immobile part of the 

 exoskeleton, need not militate against the homology, for the somewhat mobile 

 girdle of Gymuodinimn is certainly homologous with the zone of girdle plates 

 in the Peridinioidea. In view of the form and location of this projection in 

 Prorocentrum it appears that Protodinifer is nearer the Adiniferidea than is 

 OxyrrJiis, which, in the location and imperfection of the girdle, is much nearer 

 Hemidininyn than is Protodinifer. O.ryrrhis may then be regarded as a 

 more specialized and higher representative of the Protodiniferidae than is 

 Protodinifer. 



OxyrrJiis marina appears to be the only valid species in the genus. Poche 

 (1903) described 0. parasitica from the coelenteron of the Siphonophora. It is 

 a minute flagellate with two uneqiial flagella in the midventral surface. There 

 is no other evidence of its affinities to OxyrrJiis. We therefore agree with 

 Senn (1911) in excluding it from that genus, pending investigation of its 

 nucleus and flagella. Scherffel (1900) described another parasitic flagellate 

 living in the coenobia of PJiaeocystis globosa, which he called OxyrrJiis pJiaco- 

 cysticola. There is no evidence of a girdle or of a beaded nucleus in his account 

 or in his figures of this species. There are suggestions in the shape, posterior 

 brown body, and anterior tentacle-like projection, of relationships to Proto- 

 dinifer, but more investigation is needed before a decision can be made regarding 

 its true affinities. It does not appear to be an OxyrrJiis. 



Oxyrrhis marina Dujardin 

 Text figure R, 3 



Oxyrrhis marina Dujardin (1841), p. 347, pi. .5, fig. 4. 

 0. marina, Diesing (1850), p. 57; (1865), p. 79. 

 Ghjphidiirm marinum Fresenius (1865), pp. 83, 84, figs. 4-10. 

 G. marinum, Cohn (1866), pp. 295, 296, pi. 15, figs. 36, 37. 

 Oxyrrhis marina, Cicukowsky (1881), pp. 130-171, figs. 1-3. 



