PRESIDENTIAL ADDRESS. 529 
These two alternatives may be expressed graphically thus :— 
Sepiadarium Sepioloidea Sepiola 
| 
Rossia 
l 
Idiosepius | 
| | 
| 
(A) 
Sepiadarium Sepioloidea Sepiola 
| | 
| Rossia 
Idiosepius | 
| 
(B) 
These schemes are not entirely satisfactory. Certain difficulties are common 
to them both. The posterior salivary glands, which, it is assumed, were inherited 
in a fused condition from the primitive Cigopsid stem, and remain in that con- 
dition in Rossia, have been separated in Idiosepius, Sepiadarium, and Sepiola, 
as well as in Sepia and Loligo. 
Furthermore, A presents the difficulty that the fusion of the mantle with the 
head in the nuchal region has been acquired independently by Idiosepius, Sepia- 
darium and Sepioloidea, and Sepiola. 
On the other hand, B has the disadvantage of assuming that the hectocotylisa- 
tion has been transferred from the fourth to the first pair of arms independently 
in Rossta and Sepiola. 
On the whole it would appear that this is the greater difficulty of the two, for 
variations in the connections of the mantle are known to occur in other groups. 
For example, in the whole family of the Cranchiidz the mantle is fused with the 
head in the dorsal middle line, and is also united with the base of the funnel on 
either side. A similar union is found in Sepiadariuwm, though it does not oecur in 
the allied Sepioloidea, Again, in Symplectoteuthis owalaniensis a similar connection 
between the mantle and the base of the funnel occurs, though it is not found in any 
of the allied genera. If scheme A is admitted to offer the lesser of the two 
difficulties, it has the advantage of indicating that the hectocotylisation of the 
ventral arms has been directly inherited from the main stem common to Myopsids 
and (gopsids, and has only been transferred to the dorsal arms in the branch 
common to Rossia and Sepiola. One other instance has recently come to light in 
which the hectocotylisation has been transferred from the ventral to the dorsal 
arms ; [allude to the genera Calliteuthis and Histioteuthis (7) among the Gigopsida : 
they constitute the sole instance in this sub-order in which the hectocotylisation 
affects any other than the ventral pair of arms. 
On the whole we reach the conclusion that, although the variations in the 
structure and position of the hectocotylus follow pretty closely the systematic 
divisions of the Dibranchiata, we are not justified in maintaining that the position 
of the hectocotylised arm is by itself a sufficient guide to the systematic position 
of a doubtful form; it is only one of many characters that must be taken into 
consideration. 
The subject of fossil Cephalopoda has not formed any part of my own special 
researches, but a contribution has recently been made to our knowledge of these 
forms to which it seems desirable to allude, because it deals, not with systematic 
or stratigraphical facts, but with conclusions which may be drawn from shell 
structure as to the life-history and habits of certain important and interesting forms, 
1907. MM 
