544 
JOTTINGS FROM THE BIOLOGICAL LABORATORY OF 
SYDNEY UNIVERSITY. 
By Prof. William A. Haswbll, M.A., D.Sc. 
No. 18 — Note on Certaijn Points in the Arrangement and 
Structure of the Tentaculiferous Lobes in Nautilus 
pompffius. 
(Plate xlviii.) 
In writing a short account of the structure of Nautilus for a 
general work I have had occasion to examine a considerable 
number of specimens, and in doing so have noticed one or two 
points to which attention has, I think, not hitherto been directed. 
The most important of these, with which alone the present com- 
munication deals, has to do with the tentaculiferous lobes of the 
foot, and their sexual modifications. 
No fewer than three papers published or read recently deal 
with sexual differences in Nautilus. Two of these, one by 
Willey,* the other by Yayssiere,f refer only to sexual differences 
in the shell ; the third, by J. Graham Kerr, J is referred to below. 
The tentacles of Nautilus are arranged in two series — an outer, 
and an inner. With the outer series we are not at present 
concerned. The inner series exhibit a marked sexual difference in 
their arrangement. In the female this inner series consists of 
two symmetrical lateral lobes, each bearing twelve tentacles, and 
of a median (posterior) portion. In the male the two lateral 
lobes of the inner series are unsymmetrically developed, four of 
the tentacles of one side, usually the left, being modified to form 
the structure known as the spadix. 
The spadix was first described by Van der Hoeven.§ He 
calls it "a great conoid body, the length of which was nearly 2 J 
* Natural Science, June, 1895. 
t Comptes Rendus, 24th June, 1895. 
+ Zoological Society of London, Abstract of Proceedings, June 18, 1895. 
§ Trans. Zool. Soc, Vol. iv., p 27. The earlier Dutch papers are not 
accessible to me. 
