MESOZOIC AND CAINOZOIC DINOFLAGELLATE CYSTS 181 



OTHER SPECIES 



Re-examination of Baltisphaeridium ferox (Deflandre 1937a) Downie & Sarjeant 

 1963, B. tridactylites (Valensi 1955), Downie & Sarjeant, 1963 and Hystrichosphaeri- 

 dium clavigerum Deflandre 1937a, by Mr. R. J. Davey and Prof. Deflandre, has 

 determined that these species should be transferred to the genus Hystrichokolpoma. 



The remaining species attributed to this genus are H. sequanapartus, Deflandre & 

 Deflandre-Rigaud 1958, and H. poculum Maier 1959. A single specimen of a form 

 very like the former was found in the London Clay. 



