SEXUAL ACTIVITIES OF THE SQUID 349 
among both Decapoda and Octopoda in modern times, it would 
seem that structural modification probably came early. 
Possibly this modification was based upon the use of one or more 
arms as guides for the transfer of the sperm. It is possible that 
having first used the arms as guides, structural modifications and 
dexterous movements were developed as divergent methods. If 
the two methods form a linear series, there issome reason to think 
structural modifications came first.. It would seem much easier 
to explain modifications that lead to the change in the structure 
of appendages for the transfer of spermatozoa, as the grooved hec- 
tocotylized arm of Octopus or the modified abdominal appendages 
of certain Crustacea, than to explain a sudden change that would 
result in a practically unmodified arm functioning by grasping 
spermatophores of a very specialized kind, transferring them 
quickly and accurately to the required position and holding them 
there until they have had ample time to ejaculate and fix their 
contents. It seems more reasonable to suppose that an arm modi- 
fied as a machine to perform this process, with its tip serving to 
place the spermatophores in position, might in time acquire the 
necessary dexterity and then lose the modifications previously 
acquired, than to look at this as the beginning of the series. Again 
we find that in such cases as the squid, where the arm is little modi- 
fied but very dexterous, there is a special receptacle at some dis- 
tance from the opening of the oviduct that is norma ly filled with 
sperm during the breeding season. This would certainly seem to 
be a comparatively recently acquired receptacle, so the copulation 
leading to its being filled would also be considered comparatively 
recent. That this receptacle is concerned in the fertilization of 
the eggs is shown by observations made while the eggs were being 
laid. 
With no personal knowledge of the breeding habits of other 
cephalopods than the squid, it would seem more reasonable to 
consider the method of using the detachable hectocotyl of such 
forms as Tremoctopus as one extreme, the method used by Loligo 
In grasping spermatophores and transferring them directly as an- 
other extreme and the condition shown by Octopus as the modern 
greatly specialized product of a modification such as early cephal- 
