354 University of California Publications in Zoology [Vou.9 
which he assigns Plalycryphalus sethodiscus as a synonym, but 
does not figure the second species. 
The species figured appears strangely out of place among 
the trieyrtid Radiolaria with which it is grouped, and one is 
surprised that neither Haeckel nor his artist, Mr. Adolph Giltseh, 
was led to question this allocation of the organism, especially 
since Haeckel himself had previously (1873) deseribed Dictyo- 
cysta cassis (== Cyttarcylis cassis (Haeckel) Bdt.) a tintinnid 
ciliate most nearly related to the organism in question. The 
lack of clear evidence as to the differentiation of typical cephalis 
and thorax lead Haeckel (1887, p. 1298), to speculate, however, as 
to the origin of this unusual genus as follows: “‘It is possible 
that this peculiar genus has been derived from a Trieyrtid 
(Theocalyptra?) by loss of the original cephalis, and that the 
apparent large cephalis is the original thorax.’’ 
The organism in question is represented in Haeckel’s (1887) 
figure by the skeleton only. It is drawn as a fenestrated cone 
with rounded apex and narrow, flaring collar. The mesh of 
the cone (cephalis) is made up of somewhat uniform, rounded 
elements with traces of angulation or polygonal form in places, 
but with much less of the polygonal effect than in the Radiolaria 
to which Haeckel supposes it to be nearly related. The mesh 
of the rim or collar is less uniform and has seattered, irregular 
elements of larger size and irregular form. 
The species in question, Sethocephalus eucecryphalus, has not 
since been reported. 
In December of the same year in which Haeckel (1887) pub- 
lished this speeies, Daday (1887) in his Monographie der 
Familie der Tintinnodeen deseribed as Cyttarocylis cassis 
Haeckel var. plagiostoma n. var. the same organism, but does 
not refer to Haeckel’s figure, nor does any subsequent investi- 
gator of the Tintinnodea make such reference. 
The differences between the descriptions and figures of the 
two organisms as given by Haeckel and Daday are no greater 
than the variation found by monographers (Daday, 1887, Brandt, 
1907) within the individual species of Cyttarocylis. The dimen- 
sions and proportions are very similar and become more so 
if one takes the measurements of Haeckel’s figure (pl. 56, fig. 
