Mating of <i>Lymnaea stagnalis</i>. Pp is preputium = penis-carrying organ of a male role snail that transfers sperm to female role snail opening.
Joris M. Koene, Wiebe Sloot, Kora Montagne-Wajer, Scott F. Cummins, Bernard M. Degnan, John S. Smith, Gregg T. Nagle &amp; Andries ter Maat
CC BY 2.5
Koene J. M., Sloot W., Montagne-Wajer K., Cummins S. F., Degnan B. M., Smith J. S., Nagle G. T. &amp; Maat A. ter (2010). "Male Accessory Gland Protein Reduces Egg Laying in a Simultaneous Hermaphrodite". <i>PLoS ONE</i> 5(4): e10117. <a href="//doi.org/10.1371/journal.pone.0010117" class="extiw" title="doi:10.1371/journal.pone.0010117">doi:10.1371/journal.pone.0010117</a>. Figure 1A.