350 GILMAN A. DREW 
opods probably developed. This would mean that the detachable 
hectocotyl is an extreme specialization in structure and that the 
modification shown by the squid represents possibly a degenera- 
tion in structure but a remarkable specialization in habit. 
Why a form should have two methods of copulation is not at 
all clear. Certainly the introduction of the spermatophores into 
the mantle chamber to a position near the oviduct is to be con- 
sidered more primitive than their being placed in a position to 
fill a receptacle outside of the mantle chamber, but why mantle 
chamber copulation should be retained after the receptacle has 
been perfected is not clear. That mantle chamber copulation is 
not absolutely necessary for the fertilization of the eggs I think is 
proved by my observations; that it is common is certain. That 
the sperm receptacle is an improvement over the free attachment 
of the sperm reservoirs in the mantle chamber is evident from the 
longer possible retention of the sperm in the receptacle. Inalim- 
ited period after the sperm reservoirs are freed from the sperma- 
tophores, as when deposited in the mantle chamber, the sperm all 
escape and are wasted unless oviposition takes place in the mean- 
time. 
SUMMARY 
Squid have two methods of copulation. By one method sperm 
reservoirs are attached in the mantle chamber on or near the ovi- 
duct and immediately begin to discharge their contents freely in 
the water. By the other method sperm reservoirs are attached 
to the outer buccal membrane and the sperm become stored in a 
special receptacle in the membrane, which is placed opposite the 
junction of the two ventral arms and opens on its inner surface. 
The left ventral arm of the male is always used in transferring 
the spermatophores, which are grasped by the arm and transferred 
by its free movement. Ejaculation of the spermatophores is evi- 
dently started by the pull given their filaments when the arm starts 
to transfer them from the penis to the mantle chamber or buccal 
membrane. The transfer requires rapidity and dexterity and the 
spermatophores are held in position until ejaculation is complete 
and their sperm reservoirs are fastened. As many as forty sperm- 
atophores may be transferred at a time. 
