378 Dr. Reid on the Development of the 



borders to the object upon which it was deposited. The process 

 of spawning did not seem to occupy any very great length of 

 time. The other pair was seen in coitu nine days after I had 

 taken them home^ and when examined thirteen hours after this 

 neither had spawned, but two hom*s later one had spawned and the 

 other w^as spawning. The animals by spawning became consider- 

 ably reduced in size. They were kept alive for three weeks, and 

 they deposited small portions of spawn between ten and fourteen 

 days after the first spawning. It does not however appear to be 

 absolutely necessary for the production of fertile ova in all, if in 

 any of the individuals of the Nudibranchiate Mollusca, that a 

 coitus should have so shortly preceded spawning as was observed 

 in the Polycera, for an Eolis which was kept strictly confined in 

 a vessel by itself, deposited, on the tenth and again on the thirty- 

 second day of its isolation, abundance of fertile ova. During the 

 high spring tides at the end of last February, I found near low- 

 water mark several large assemblages of Goniodoris Barvicensis 

 and Doris bilamellata among the rocks, collected for the purpose 

 of breeding*. In one of these groups there must have been at 

 least between sixty and seventy individuals of the G. Barvicensis j 

 and abundance of their spawn adhered to the surface of the rocks, 

 and in one place a portion about six inches square was almost 

 completely covered by it. Many of the Doris bilamellata had 

 also spawned, and were collected in smaller, more numerous and 

 scattered gi-oups, the greater number of which were farther from 

 low-water mark and in more exposed situations than those of 

 the G. Barvicensis. These assemblages do not break up for some 

 time, but continue to occupy nearly the same position, and the 

 animals composing them spawn more than once. I found some 

 individuals still lingering among the rocks, and recent spawn de- 

 posited, as late as the end of April. Several pairs of the Doris 

 tuherculata were also observed, and I procured four specimens 

 of Dendronotus arborescens and two specimens of the Eolis men- 

 tioned above. The individuals of the two last genera mentioned 

 were not found in pairs, and these, along with several specimens 

 of Goniodoris Barvicensis and Doris bilamellata, were taken home 

 and kept until they had spawned. About the same time I pro- 

 cured several specimens of Doto coronata from the deep sea ad- 

 hering to Plumularia falcata and Thuiaria thnia, which were also 

 kept alive, and began to spawn about the middle of March. Near 

 the end of March I found a considerable quantity of the spawn 

 of the Doris tuberculata adhering to the under surface of the 

 ledges of rock near low-water mark. 



The spawn of the Doris bilamellata, D. tuberculata, Doto coro- 



* From the unusual mildness of this spring, the breeding-season may have 

 commenced earlier than usual. 



