198 WHEELER. [Vor. IX. 
the location of each tentacle, part of these being embedded in 
the bases of the tentacles themselves. Two other more sporadic 
clusters of eye-spots lie in front of and nearer the median line, 
extending forward from the anterior edge of the brain. In 
most, if not all, other species of Planocera hitherto described, 
these mesial clusters extend much further back between the 
tentacles. 
Owing to the lack of pigment, the nervous system may be 
traced without difficulty, especially in young specimens. It 
agrees so closely with Lang’s description and figures of the 
nervous system of Planocera Graffit that I deem a considera- 
tion of it here unnecessary. It is perhaps well to note in 
passing that remarkably clear pictures of the beautiful plexus 
and its connection with the brain may be obtained by killing in 
hot corrosive sublimate, staining for 12 hours in Czokor’s alum 
cochineal and, after dehydrating, mounting in gum sandarac 
dissolved in absolute alcohol. 
The reproductive organs are interesting on account of their 
remarkable simplicity. I shall not describe the ovaries and 
testes and their collecting capillaries (Sammelcapillaren and 
Eileiter of Lang), as they appear to agree closely with their 
homologues in other Planocerids. The two large, convoluted 
spermatic canals (sc) run one on either side of the pharynx. 
They stain deeply, being puffed out with masses of mature 
spermatozoa in all the specimens which I have examined. 
Posteriorly they are continued as the vasa deferentia (vd) 
which unite in the median line near the hind edge of the penis- 
bulb. At their point of union they open by a very short duct 
into the styliform penis (f). I have failed to find any traces 
of a seminal vesicle or granule gland (Kornerdriise), although 
I have devoted considerable study to sections and specimens 
mounted in toto. The absence of these two accessory male 
organs is noteworthy when their all but universal occurrence 
in the Polycladidea is borne in mind. According to Lang (p. 
43) the granule gland is lacking only in the genus Axonymus. 
The female reproductive organs are similarly simplified. The 
two uteri (), which usually in the adult contain a considerable 
number of mature ova, are continued back as two delicate 
