ON SOME OIGOPSID CUTTLE EISHES. 
89 
though a strong nerve supply exists in these organs. Possibly 
they have changed their function and become tactile in nature, 
in Chiroteuthis at least. 
I hope, however, at some future date to be able to give 
some further account of these organs. 
Taking another set of forms we can pass from the olfactory 
ridges on the embryo of Ommastrephes to its adult stage, 
where there is still a specialised mass of cells similar to those 
of Verania at the base of the ridge, as I was enabled to find in 
sections of the ridge. 
Then in Loligo we get the olfactory organ partly invagi- 
nated but keeping the same relation to the ridges on the 
neck, which become now specialised into an auricular, or better, 
a protective crest (PI. X, fig. 6). 
Verrill (6) speaking of the auditory pore of Omma- 
strephes illecebrosa, must surely mean the structure which 
is generally looked upon in Loligo and Sepia as an olfactory 
pit, or, at least, as a sense organ, which is of the nature of 
an olfactory or gustatory organ. 
In Sepia sections of this pit show a similar structure to the 
modified epithelium before mentioned, and the presence of 
ciliated cells in large numbers indicate that a current must be 
constantly kept up in the interior of the pit, bringing olfactory 
particles to the sensory cells. 
In Octopus and Eledone the pit is not protected by a crest, 
but situated in an equally well-protected spot at the junction 
of the mantle with the neck. In Octopus the pit is lined with 
epithelium exactly like that of Sepia, so I think this olfactory 
organ may be traced successively in the different groups of 
Cephalopoda from the spoon-shaped organs of Chiroteuthis 
to the invagination of Sepia and Octopus, both being the 
extreme developments of the olfactory patches or cushions 
seen in Verania. The series reminds one of the transition of 
the olfactory organs of fishes from external processes to pits, 
described by Professor Wiedersheim last year in his paper 
before the British Association at Manchester. 
The fastening of the mantle in Verania consists of a simple 
