kofoid: new species of dinoflagellates. 205 



postero-ventral fin, in the absence of reticulations on the fins, and in the 

 presence of a hyaline border on the anterior margin of the posterior collar. 

 Both dorsal and ventral collar clefts in both collars are closed by delicate 

 hyaline membranes. 



Length, 64 fi ; dorso-ventral diameter of body, 33 fi. 



Station, 4711. 



Histioneis pulchra, sp. nov. 



Plate 16, Fig. 90. 



A medium-sized species of the general form of H. mitchellana but differing 

 from it in the character of the reticulations of the wings and collars. In H. 

 pulchra the reticulations are coarse, irregular, and more or less incomplete. 

 They are found on the anterior parts of the two collars, on the posterior part 

 of the ventral, and on the posterior wings. In H. mitchellana the reticulations 

 are fine, delicate, and more or less regular. 



Length, 135 fi] dorso-ventral diameter, 60 fi. 



Station, 4730, 4734, 4742. 



Histioneis reticulata, sp. nov. 



Plate 15, Fig. 95. 



A small species resembling H. crateriformis Stein but differing from it in the 

 much lower anterior collar, a higher, more recurved anterior process from the 

 body, in the presence of a subregular polygonal reticulum on parts of the pos- 

 terior collar and on the ventral fins, and in its straight posterior rib. 



Both ventral fins are relatively low. The left has two ribs, both of which 

 are straight. The middorsal and midventral clefts of the posterior collar are 

 both closed by membranes, the former with five equidistant transverse ribs 

 running across the closing membrane. 



Length, 115 /x ; dorso-ventral diameter, 85 fi. 



Stations, 4699. 



Ornithocercus carolinae, sp. nov. 



Plate 15, Fig. 92. 



A medium-sized species resembling 0. magnificus but differing from it in 

 the following particulars : the posterior wing has 12-14, rarely 9-15, light 

 ribs of uniform size evenly distributed without prominent midribs to the 

 marginal and median projections. These ribs are more slender and more 

 numerous than those in 0. magnificus. The anterior collar has numerous 

 (twenty or more) primary ribs, with intercalated secondary and tertiary ones. 

 The right and left ventral wings are in old (?) individuals reticulated. Re- 

 ticulations may also be found in the middorsal region of the posterior collar, at 

 the base of the anterior one, and on the dorsal margin of the posterior wing. 



Length, 100 /u; dorso-ventral diameter, 65 fi. 



Stations, 4719, 4721, 4722, 4724, 4740. 



