kofoid: new species of dinoflagellates. 203 



Triposolenia ambulatrix, sp. nov. 



Plate 4, Fig. 24. 



A medium-sized species of the T. bicornis type with both antapical horns 

 deflected dorsally, especially the dorsal one. 



The midbody is laterally compressed, subtriangular in lateral view with 

 anterior process and antapicals arising from the angles as in T. bicornis. Its 

 sides are all convex and the anterior process arises abruptly from somewhat 

 squarish shoulders. The head is spheroidal, and the neck long, slender, and 

 convex ventral ly. There is a large ventral protuberance about the flagellar 

 pore. 



The ventral antapical is abruptly deflected postero-dorsally and forms a slight 

 sigmoid curve which is less pronounced distally. Its tip is acute and it is de- 

 flected to the right distally. The dorsal antapical is not bent to form a balanced 

 horn, in reverse, as in T. bicornis, but is thrown dorso-posteriorly with a slight 

 anterior convexity. Its tip is truncate and bears two minute spinules. It is 

 deflected to the left distally. There are a few distally located tubercles on the 

 dorsal and ventral margins of the antapicals. 



Length to postmargin of midbody, 95 /x ; to tip of ventral antapical, 165 p. 



Station, 4711. 



Histioneis carinata, sp. nov. 



Plate 16, Fig. 98. 



Somewhat resembling H. biremis Stein as figured by Murray and Whitting * 

 in its bird-shaped body, and in the absence of a postero-dorsal prolongation. 

 The anterior collar is less abundantly ribbed, and both it and the posterior one 

 are asymmetrical, being lower at the right end. There is no fin dorsal to the 

 posterior rib. The areoles on the midbody are more numerous, being 11 by 

 20 to 8 by 15 in H. biremis. There is no ventro-marginal rib in the posterior 

 wing. 



Length, 90 \i ; dorso-ventral diameter of midbody, 50 /x. 



Station, 4724. 



Histioneis garretti, sp. nov. 



Plate 16, Fig. 97. 



A small species resembling H. para Murr. et Whitt. but differing from it in 

 the presence of a fin on the dorsal side of the posterior rib. There are reticu- 

 lations in the basal part of the anterior collar, and along the dorsal ribs of the 

 posterior collar. The ventral and posterior fins are also more or less reticulate. 

 Both collars closed ventrally and dorsally. 



Length, 63 /x ; dorso-ventral diameter, 38 /x. 



Station, 4732. 



1 New Peridiniaceae from the Atlantic. Trans. Linn. Soc. Lond. Bot., 32, 

 Plate 32, Fig. 6. 



