KOFOID AND MICHENER: DINOFLAGELLATES. 291 



Phalacroma praetexta, sp. nov. 



A small species somewhat the shape of P. vastum Schiitt and P. circum- 

 cincta, sp. nov. with slightly premedian girdle and Protoceratium-like, coarse 

 reticulations. Body subcircular in lateral view, in dorsal view biconical with 

 broadly rounded ends. Length, 1.13 times dorso-ventral diameter. Trans- 

 diameter, in wide individual measured, equalling dorso-ventral. Girdle 

 indents the epitheca, its posterior ridge about equatorial. Girdle lists low, 

 horizontal, ribbed, 0.5 girdle width high. Ventral fins very small, less than 

 girdle width in height, with single weak spine at fission line. Surface heavily 

 reticulate with distinct Protoceratium-like mesh, 15 behind girdle, of somewhat 

 irregular pore-free polygons. Girdle heavily reticulate. Girdle ribs from 

 nodes. 



Length 60 fx; dorso-ventral diameter 55 n) transdiameter, 51 /i. 



Sta. 4742. 



Phalacroma pulchra, sp. nov. 



A variable species with outline in lateral view subsemicircular posteriorly, 

 somewhat flattened anteriorly, the outline scarcely broken by the girdle. 

 Length about equalling greatest dorso-ventral diameter, rarely 1.3, in which 

 case the antapical region is slightly drawn out. Epitheca, measured from base 

 of anterior collar, never over 0.3 of total length and usually much less. Collars 

 low and spreading, without ribs. Posterior spine of ventral fin somewhat 

 exceeding 0.35 of total length of body in length. Posterior spine long, attain- 

 ing 0.4 of total length. Ventral, posterior, and low dorsal fin sometimes 

 united in continuous sagittal structure, rarely with reticulations or secondary 

 riblets. Surface smooth with regularly spaced pores, 12 across the side, or 

 finely reticulate. 



Length, with spines 74 n, without 51 fj.', dorso-ventral diameter 51 /x. 



Sta. 4699. 



Phalacroma turbinea, sp. nov. 



A medium sized, elongated, top-shaped, very coarsely reticulate species 

 resembling remotely P. reticulata Kofoid. Remarkable for the large size of 

 the meshes. Body elongated, spreading at girdle. Length 1.86 dorso- 

 ventral diameters. Girdle section (in individual measured) subcircular, 

 transdiameter 1.21 dorso-ventral diameters. Sides in lateral view concave, 

 tapering to rounded antapex 1.5 girdle widths across. Epitheca a low cone, 

 2 girdle widths high, with rounded apex. Surface non-porulate, with Proto- 

 ceratium-like mesh of huge dimensions, 5 across face at girdle, 28 on right 

 side of hypotheca, and 11 on right side of epitheca. The sagittal region has a 

 broad, ladder-like series of rectangular meshes, 14 on dorsal and 12 on ventral 



