The Cephalic Appendages of the Gymnosomatous 
Pteropoda, and especially of Clione. 
By 
Paul Pelseneer, D.Sc,, 
Brussels. 
With Plate XXXV. 
Eschricht formerly made known, on the three pairs of 
cephaloconi (“ Kopfkegel ”) of Clione borealis, some struc- 
tures which he described and represented as real suckers ; at 
the same time he drew attention to the analogy of their situa- 
tion with that of the suckers of the Cephalopoda. 1 
This fact was of great importance, since it accorded with the 
presence of suckers on the two buccal appendages of another 
Gymnosomate, viz. Pneum odermon, and gave great support 
to the opinion expressed by R.. Leuckart, that the six conical 
appendages of the head of Clione correspond with the arms 
of the Cephalopoda. 2 
From that time the assertion that Clione possesses aceta- 
buliferous appendages has been admitted everywhere, and it 
is found reproduced in the most valuable and most recent 
works. 
However, the excessive smallness of the structures which 
Eschricht had described as suckers (he attributes to them 
0005'" of diameter) permitted one to call in question their 
assimilation with the suckers of Pneumodermon and of the 
1 Eschricht, * Anatomisclie Untersuchungen iiber Clione borealis,’ p. 9. 
2 It. Leuckart, * Ueber die Morpbologie und die Verwaudscbaftsverbalt- 
nisse der Wirbellose Thiere.’ 
