kofoid: new species of dinoflagellates. 167 



Outline of the couplet and of long-homed single individuals nearly circular or 

 elliptical. Midbody more convex on inner than on outer face of the arc, its 

 length 1.7-2 times its transdiameter. The horns are tapering, sharp pointed, 

 their distal ends sharply incurved, or with sigmoid flexure. Their length 

 4.5-10 transdiameters. The two horns are unequal in length, one being 1.1 

 times th-^ length of the other. The long and the short horns are joined in the 

 couplets. 



Differs from P. hamulus in the larger size, less abrupt flexure of the arms, in 

 the absence of the sharp double flexure at the midbody, and in the fact that the 

 arms are more nearly equal in length. 



Long axis of ellipse, of single or yoked individuals, 315-580 /x; transdiameter 

 of midbody, 40-62 ft. 



Stations, 4691, 4728, 4740. 



Pyrocystis robusta, sp. nov. 



Plate 1, Fig. 5. 



A small species of robust habit, deeply crescentic. Differs from P. lunula 

 in its greater curvature, stouter body, and absence of central expansion. 



Body fusiform but bent into a deep crescent whose tips nearly meet or even 

 overlap. The convex margin is circular in outline, and the gap between the 

 tips is less than 0.25 of the circumference. The diameter of the spherical or 

 oval area enclosed by the crescent is 0.5, rarely 0.3-0.4, of the diameter of the 

 larger circle. Greatest width at the middle of the body, tapering gradually to 

 the tips. Width, 0.14-0.22 of the axial length. 



Diameter of outer circle, 77-215 /x ; wddth of body at middle, 26-90 /x. 



Stations, 4728, 4740. 



Pouchetia panamensis, sp. nov. 



Plate 1, Fig. 7- 



A minute species with symmetrical ellipsoidal body and minute lens and 

 melanosome. 



Body elongated, ellipsoidal, its length 1.5 times its transdiameter. Epicone 

 about equal to hypocone. Apex broadly rounded, antapex also rounded, 

 flattened ventrally. Girdle very oblique, transverse furrow very wide, 0.2 of 

 a transdiameter in width, deeply impressed, forming a descending right spiral, 

 displaced 6.5 times its width, and with an overhang of 0.25 of the circumfer- 

 ence. Longitudinal furrow, 0.25 of the width of the transverse furrow extend- 

 ing from near the apex to the antapex, where it widens and spreads in two 

 lateral bifurcations, twisted 0.30 of the circumference around the body. 

 Transverse flagellum arises at anterior junction and longitudinal at posterior 

 junction of furrows. Ellipsoidal nucleus in hypocone, stout crescentic melan- 

 osome with minute spheroidal lens. 



Length, 34 ft; transdiameter, 21 /i. 



Anchorage at Panama. 



