6 ART. 4. N. YATSU : 



I have never met with larvae at any other time during the year. 

 The spawning season is about one month and a half later than 

 that of Terebratulina, which, according to Morse, spawns at the 

 end of May and in the early part of June at Eastport. As to 

 how many times LinguJa spawns in a season I have not yet 

 any positive proof, as the young free-swimming larvae have not 

 been caught in the past three years in sufficient number to enable 

 me to decide the question. I can, however, safely declare that 

 the youngest larvae appear at least twice in a season. Professor 

 Mitsukuri informs me that in his experience the youngest larvae 

 appear after every spring tide. And this being the case, the 

 spawning must occur twice a month i.e. three or four times 

 during a season. 



III. MATERIALS AND METHODS. 



Early stages of the embryo were secured from the two 

 spawnings described above. The eggs mixed with sperm were 

 kept in several chemically clean glass vessels with covers, which 

 were placed within another larger vessel filled with cold fresh- 

 water in order to keep the inner vessel as far as possible at a low 

 temperature, as we usually do at the station in rearing various 

 larvae during the hot season. In both cases in spite of the 

 utmost care it became most difficult after three days to keep the 

 embryos living, and on the fourth morning the last of the 

 materials was killed. 



Artificial fertilization was afterward tried several times, but 

 always in vain, owing to difficulties of obtaining mature sexual 

 elements simultaneously and of separating the eggs from the 



