492 
PAUL PELSENEEE. 
Cephalopoda, the more so as Hobboll, who has observed Clione 
living, and has often seen their cephaloconi expanded, has 
never remarked that these animals fixed themselves by these 
appendages, 1 while several naturalists have seen Pneumoder- 
mon in life, and have noticed that it frequently fixes itself 
with the aid of its acetabuliferous appendages. 
Therefore, during the sojourn which I made in the winter of 
1884-85 at the zoological laboratory of University College 
(London), Professor Ray Lankester proposed to me to study 
the structure of the cephaloconi of Clione. 
Having set to work, I immediately saw that in a large number 
of well-known and even very recent works great confusion pre- 
vailed on the cephalic appendages of Clione. The reason of 
this is specially to be found in the imperfection of the original 
figures, which are generally obscure on the subject; and those 
which are most often reproduced are just the most defective, 2 
for they give a very bad idea of the cephalic appendages of 
Clione, or are even absolutely incomprehensible on this 
point. 
Those of Eschricht are small, and also difficult to under- 
stand, so that the reproductions which have been made of 
them are inexact, and, as Keferstein has remarked, “ all those 
processes which have been named tentacles by Eschricht want 
a new description/’ 3 
"When I had comparatively examined other Gymnosomata, 
I remarked that there also a confusion quite as great existed 
on the cephalic appendages, the more so since the original 
authors do not agree on this question. 
In order to dispel the confusion which exists on this sub- 
ject, I have thought useful to represent on a rather large 
scale, and under different aspects, the cephalic part of some 
1 Eschricht, loc. cit., p. 9. 
2 For example, the figure of Clione given by Rang (Rang et Souleyet, 
‘ Histoire naturelle des Mollusques Pteropodes,’ pi. vii, fig. 9), reproduced by 
Keferstein (Bronn’s ‘ Thierreich ’), by Claus (‘ Elementary Text-Book of 
Zoology ’), &c. 
3 Keferstein, Bronn’s ‘ Thierreich/ Abth. iii, p. G13. 
