"Vol. 3] Kofoid. — Triposolenia. 101 



individuals it is possible to find small irregular, pale, yellowish- 

 green chromatophores {clir. PI. 15, fig. 2) with a peripheral 

 distribution in the cell. No species appears to possess these struc- 

 tures with a characteristic pattern in either form or distribution. 

 Reproduction, either sexual or asexual, has not been observed. 



Surface temperatures of the Pacific in the San Diego region 

 range from 14°-24° C. with a predominant temperature of 18°- 

 20° C. throughout much of the year. At 100 fathoms the tem- 

 perature has been found to range from 9.75°-13° C. No seasonal 

 restrictions in the distribution of the species of Triposolenia ap- 

 pear in the scanty data of their occurrence in the waters off San 

 Diego. The more common species, T. hiconiis, T. truncata, and 

 T. ramiciformis, are found in both summer and winter plankton. 

 T. deprcssa and T. exilis have thus far been found very sparingly 

 in the San Diego plankton. 



Triposolenia gen. no v. 



Dinophysidac Avith subequal valves, transverse girdle encir- 

 cling a small head, neck elongated, oblique to anterior process 

 which arises obliquely from a laterally compressed enlarged mid- 

 body. Two- antapical horns, spreading-, curved, approximately 

 balanced, the dorsal a trifle shorter than the ventral. The an- 

 tapical tips simple, with or without spinules or projecting tu- 

 bercles or major flexures, often with a distal sinistral deflection, 

 thecal wall structureless or pitted. Lists hyaline, ribbed, not ex- 

 cessively developed. Chromatophores yellowish green, if present. 

 In oceanic plankton of warm-temperate and tropical seas in the 

 deeper levels, rarely at the surface. 



Types of the species here described are in the collections of 

 the Zoological Department of the University of California. 



Posterocornia subgen. nov. Antapicals arising from posterior 

 part of centrally located midbody. 



Ramiciformia subgen. nov. Antapicals arising from anterior 

 part of pendant midbody. 



