278 bulletin: museum of comparative zoology. 



wider along meridional sutures, smaller in center of plates. Three rows 

 and an apical group of polygons on epitheca, five and an antapical group on 

 hypotheca. Numerous minute scattered pores. 

 Length, 85 /j.; transdiameter, 70 n. 



Sta. 4697. 



Protoceratium globosum, sp. nov. 



A spheroidal species of medium size, with delicate polygonal mesh of medium 

 size, without lists or spines. Body almost perfectly spherical, except for 

 depressed ventral area. Length, 1.11 transdiameters. Epitheca equals 

 hypotheca, both apex and antapex slightly flattened. Apical area minute. 

 Girdle descending, displaced 0.66 girdle width, its furrow scarcely at all im- 

 pressed, guarded by low, hyaline, ribbed lists. Ventral area impressed, 

 expanding to the right, its length from anterior girdle lists 0.57 transdiameter. 

 Surface covered with a network of irregular polygons, sutures faint. Polygons 

 numerous, about five rows and an apical group on epitheca, and six and an 

 antapical group on hypotheca. No pores. Very translucent. 



Length, 58 n\ transdiameter, 52 /x. 



Sta. 4737. 



Protoceratium pellucidissimum, sp. nov. 



A minute spheroidal species with apical horn, remarkably large polygonal 

 mesh, and excessive transparency. Body subspheroidal. Length 1.13 

 transdiameters, girdle subcircular with slight ventral flattening. Epitheca 

 exceeded by hypotheca, its altitude 0.45 transdiameter, subconical, sides 

 somewhat convex, contracted distally into an asymmetrical apical horn 1 

 girdle width in height and a small, somewhat oblique apex. Hypotheca 

 hemispherical, its altitude 0.6 transdiameter. Girdle descending, displaced 1 

 girdle width, its furrow not impressed, guarded by hyaline lists with few ribs. 

 Ventral area short and narrow, its length from anterior girdle list but 0.5 

 transdiameter and its width 1 girdle width, distally contracted. Surface 

 covered with very large polygonal mesh of delicate character. Two rows and 

 an apical group on epitheca, and two and an antapical on the hypotheca. 

 Sutures not visible, antapical list with spinules present. No pores. Exces- 

 sively transparent. 



Length, 50 fx; transdiameter, 44 /x. 



Sta. 4701. 



Possibly not a Protoceratium. 



