(A) Gross appearance of the oviposition site. A torrent winds through the forest floor. The torrent has a 119.7 m-long distance of rapidly-flowing stream due to melting snow, which is heading down on the surface between subterranean streams. A wetland with a little body of water is spread above the place where the onset of the surface stream is recognized. Adult males and females immigrate toward the stream sides during November and hibernate in the water.

(B) Two pairs of egg sacs, the adhesive tips of which were attached to the upside of rocks in the torrent (water temperature of 8.8 C). These egg sacs were deposited among sands and gravel accumulated on the rocks. Embryonic development was each in a 4-cell stage or a blastoporic-lip stage. The number of eggs in a pair of egg sacs with the 4-cell stage was 47 (22 and 25 eggs each, including an unfertilized egg) and that with the blastoporic-lip stage was 49 (24 and 25 eggs each, including an unfertilized egg).

Accompanied Research Collaborators: Masaichi Kakegawa, Fujio Kishi, Kenji Numata, Yuko Saikawa, and an anonymous person (alphabetical order).