VoL. 2 | Kofoid.—On Heterodinium. 353 
Heterodinium milneri (Murr. et Whitt.). 
Peridinium Milneri Murray and Whitting (’99), p. 327, Pl. 29, figs. 3a, b. 
The characteristic Heterodinium structures are not clearly 
shown in Murray and Whitting’s figures. There is only a sug- 
gestion of the midventral suture of the epitheca and a markedly 
deficient posterior list of the transverse furrow. The ventral pit 
is lacking and the plates are incompletely shown. 
The species is characterized by its spheroidal rotund body, 
premedian girdle with wide displacement and considerable over- 
lap of the ends of the transverse furrow, wide zones along suture 
lines free from reticulations, and coarsely reticulated plates... It 
is closely related to H. murrayt. 
Reported from tropical Atlantic in 29°-31° N. 
Heterodinium murrayi nom. nov. 
Peridinium tripos Murray and Whitting (’99), p. 327, Pl. 30, figs. 4a, b. 
non P. tripos (Muller), Ehrenberg (’33), p. 272 = (Ceratiwm tripos). 
The specific name tripos must be rejected as it was previously 
introduced into the genus Peridinium by Ehrenberg’s (733) 
transfer of Cercaria tripos of O. F. Miiller (1786) to the genus 
Peridinum. As figured by Murray and Whitting (’99) this 
species shows almost none of the generic characters except the 
very deficient posterior list of the transverse furrow. The ven- 
tral pit is questionably figured and no trace of the plates is 
shown. The only evidence of the presence of the left interealary 
is the shifting of the apex to the right. 
The species is characterized by its small size, rotund body, 
large and few subregular polygonal reticulations with a coarse 
mesh which hide the sutures and cover the whole theca. The 
oirdle is premedian and the transverse furrow is much displaced 
and has considerable overhang... The apex is somewhat con- 
tracted and the antapicals bear two short finned spinules on the 
left and one on the right. The anterior list of the transverse 
furrow is membranous. There are no antapical horns. 
Reported from the tropical Atlantie in 14°-31° N. 
