KOPOID AND SWEZY: UNARMOKED DINOFLAGELLATA 349 



This subgenus includes all the species which do not show special differen- 

 tiation in the form of the liody or the extreme amount of torsion, the greatest 

 amount lieing that indicated by two (or at the most 2.5 turns) turns of the 

 girdle. It is consequently the largest subgenus in number of species. These 

 fall natiu'ally into three groups according to the amount of torsion of the body. 

 The first group, which we term the C. miniatum group, has a torsion of the 

 body as shown in the girdle of 1.5 turns. It includes C. miniatum sp. nov., C. 

 sciutillaus sp. nov., C. tHrbineum sp. nov., C. catouitum Okanmra, C. volutum 

 sp. nov., and C. pirum (Schiitt). This group as a whole lies near the border- 

 line separating this genus from Gyrodinium. It also contains the only species 

 with striate surface, a striking Gurodinium cliaracteristic. 



The second group, the CochJodiiiit(m strangulatutn group, has a torsion of 

 about 1.7 turns of the girdle. It contains C. strangulatum Schiitt, C. constric- 

 fiim (Schiitt), C. pellucidum Lohmann, C. conspiratum sp. nov., and C. cereum 

 sp. nov. 



The third group, the C. citron group, has a torsion of the body as indicated 

 by about 2 turns of the girdle. It includes C. citron sp. nov., C. leboiirae sp. 

 nov., C. faurei sp. nov., C. clarissimum sp. nov., C. archimedes (Pouchet), C. 

 virescens sp. nov., C. radiatum sp. nov., C. atromaculatum sp. nov., and prob- 

 aldy C. elongatum sp. nov. 



Subgenus 2. Glyphodinium subgen. nov. 



Body as^anmetrical, excavated sinistroventrally, arched dextrodorsally, more 

 or less deeply incised by the sulcus, girdle of 1.5 to 1.6 turns. Type species, 

 Cochlodinium cavatmn sp. nov. 



This subgenus includes a small group of species with asymmetrical, more 

 or less excavated and constricted body. It includes Cochlodinium geminatum 

 (Schiitt), C. schuetti sp. nov., C. rosaceum. sp. nov., C. vinctum sp. nov., C. con- 

 volutum sp. nov., G. helix (Pouchet), C. cavatum sp. nov., and G. distort iim 

 sp. nov. These species form an orthogenetic series of increasing curvature and 

 distortion, culminating in the huge, much distorted and highly colored G. 

 distortum. 



Subgenus 3. Polydinium subgen. nov. 



Body elongate, fusiform, its length more than 2 transdiameters, girdle a 

 descending left spiral of more than 3 turns, sulcus with more than 2 turns. 

 Type species Cochlodinium augustum sp. nov. 



This subgenus includes only those species with the extreme amount of torsion 

 of the body, as indicated by three or more turns of the girdle. It includes in 

 conso([uence the most higlily differentiated species, in tliis particidar, in the 

 genus. As might l)e expected, the numl)er of species therein is small. It con- 

 tains only two species, Cochlodinium august um, the type, and C. pulcheUum 

 Lebour. 



