KOFOID AND MICHENER: DINOFLAGELLATES. 281 



Ventral notch long, narrow, its length 0.22 transdiameter. Surface finely 

 and faintly reticulated with pores near nodes. Sutures marked by light rib. 

 No intercalary bands seen. 



Length, 74 n; transdiameter, 44 n. 



Sta. 4705. 



Peridinium corniculum, sp. nov. 



A small, spheroidal species with very small, elongated apical horn, trans- 

 verse ascending girdle, displaced one girdle width, and two slender antapical 

 spines. Differs from P. globulus Stein and P. quarnerense (Br. Schroder) 

 Broch in less displaced girdle, longer apical horn, and straighter ventral area; 

 from P. globulus var. Karsten in longer apical, structure at girdle junction, 

 and in two instead of four antapical spines; from P. nodulosum in size, in 

 longer apical, and in surface markings. Midbody nearly spherical, length 

 1.04 transdiameters. Epitheca exceeds hypotheca, both hemispherical. 

 Altitude of epitheca (excluding horn) 0.6, and of hypotheca (excluding spines) 

 0.38 transdiameter. Apical horn abruptly differentiated, a flaring tube 1.55 

 girdle widths in length and 0.33 to 0.66 in diameter with ventral notch running 

 its whole length and widening distally, tilted to right. Antapical spines 

 solid, finned, 2 girdle widths in length and 2 apart at base, slightly spreading, 

 arising from edges of ventral area. Girdle and ventral area as in P. nodulosum. 

 Surface faintly reticulate, sutures marked by single rib with striae on one side 

 giving a pinnate appearance to these tracts. 



Length, of midbody, 51 /i, total, 67 fi; transdiameter, 55 /z. 



Sta. 4619. 



Peridinium hyalinum, sp. nov. 



A minute, plain, ellipsoidal species with equatorial, scarcely displaced 

 girdle, without horns or spines. Resembles somewhat Faure-Fremiet's P. 

 indetermine (1908), pi. 16, fig. 18, but differs in the absence of apical projection, 

 distal asymmetry of central area, and in having a very slight displacement 

 of the girdle. Body ellipsoidal, its length 1.16 transdiameters. Girdle 

 section circular with slight ventral depression. Epitheca slightly exceeded 

 by hypotheca, its altitude 0.5 transdiameter, subhemispherical, with slight 

 suggestion of apical contraction. Ventral notch 0.6 girdle width long. Hypo- 

 theca hemispherical, its altitude 1.05 transdiameters. Girdle equatorial, 

 descending, displaced only 0.4 girdle widths, its furrow very shallow, with 

 low ridges but no lists. Ventral area nearly straight, reaching postmargin, 

 slightly expanded to the left, with low lists on either side. Three dorsal 

 anterior intercalary plates. Surface smooth and hyaline. 



Length, 30 n; transdiameter, 27 /u. 



Sta. 4720. 



