BEPRODUCTION — PAIRING AND ITS PRELUDES. 
373 
tentacles, which are curiously drooping at the tips during this period, 
possibly from the partial withdrawal of the blood to other organs ; 
they also frequently simultaneously elevate the anterior portion of 
their bodies, bringing the raised part into 
close, but temporary, apposition, touching 
p and rubbing against each other and probably 
increasing the mutual excitement by the 
use of their love darts. 
In the Dioeciate species and certain of the 
Monceciate Ditreinata, the conjugation is 
simple, one individual being male or acting 
as male only, the partner being female or 
fulfilling feminine duties exclusively, the 
necessary conjunction being effected usually 
after probably some preliminary co(iueting. 
In the Monoecia, the conjugation is 
generally more complex, as fertilization is 
reciprocal in many species, each individual 
simultaneously fulfilling the role of both 
male and female with another individual. 
The amorous caresses of the Monoecia, which 
precede their conjugation, are also striking 
and long continued, and may, in some 
species, be continued for the space of ten 
hours, certain highly specialized and remark- 
able organs, the Egersidia, being developed 
for excitatoiy purposes. 
In Limax maxhnus and certain other 
species, the prospective pair after their 
voluptuous preludes and circular promenade, suspend themselves 
heads downward from some suitable spot by a conjoined strand of 
mucus mutually intertwining their bodies and 
the essential organs being exserted and also 
externally intertwined in a very complicated 
manner during the act. 
In the Ditremate Limmva although the 
effect of the pairing of two individuals is that 
one only is fertilized, as in the Dioecia, yet on account of the widely 
separated apertures other individuals may join the original pair and 
Fig. 689. — Pairing of Limax 
maximus L., slightly modified 
from a nature sketch by L. E. 
Adams, B.A. 
Fig. 690. — Pairing of 
Limmca pcregra (Mull.). 
