158 
Traunfels (1902) mention tentacles in his L. borneensis. In spite of 
this it does not seem improbable to me that traces of rudimentary 
tentacles may be found in this genus, at least in the form of rudi¬ 
ments, marked by a glandless epidermis above the tentacular eye- 
groups. To clearly demonstrate such a condition it is necessary to 
examine sections through the body-region in question. Since this 
has not been made, I must regard the case as unsettled. 
Cerebral eyes. In the gQnus Stylochus there are usually two 
elongated groups of eyes in the region of the brain. Most fre- 
quently they are well separated from each other (for instance, 5. 
djiboutiensis Meixner, pusillus Bock, ijimai Yeri & Kaburaki), but 
may be fused posteriorly (for instance, 5'. arenosus Willey, cinereus 
Willey, and zebra (Verrill). In 5. orientalis var. splendida Bock and 
5. rutilus Yeri & Kaburaki they have blended into one group. The 
cerebral eyes usually occur in a large quantity. They are few in 
S. plessisi Lang, vesiculatus ^acubovra, tauricus jacuhovra, and parti- 
cularly so in pusillus Bock. 
In a few cases further particulars as to the cerebral groups of 
the eyes in unmistakeable Stylochus-sy)QC\QS do not exist. In regard 
to 5. zanzibaricus, Laidlaw (1903) positively States that he has not 
found „any definite group of brain-eyes“. A total absence of these 
eyes seems very improbable to me, until further investigations 
are made; the ocelli indicated back of the tentacles on Laidlaw’s text- 
fig. 5 (1. c.) possibly represent cerebral eyes. 
Two more or less distinctly separated cerebral eye-clusters are 
also found in Meixneria, Par asty lochus, Idioplanoides atlanticum 
(Bock 1913), Limnostylochiis borneensis (Stummer-Traunfels 1902),. 
and amarus (Kaburaki 1918), as well as in Ilyplana, Leptostylochus, 
and Kaburakia. 
In Cryptophallus wahlbergi Bock 1913 and Idioplana austra- 
liensis Woodworth 1898, the brain- eyes fuse into one single group. 
Laidlaw (1904, p. 128) likewise mentions only scattered cerebral 
eyes in the case of Idioplanoides insignis, and the same condition 
exists in Lim nosty lochus annandalei (Kaburaki 1918). 
Frontal eyes. The group designaled frontal eyes includes those 
few or numerous scattered ocelli located at the anterior end of the body 
that can neither be considered members of the marginal, cerebral, 
nor tentacular eye-groups. They connect the cerebral eye-clusters 
