6 JOURNAL OF THE [January^ 



expiration of five hours, and the termination of its labor, the in- 

 terval had vanished altogether, and the junction of the case with 

 the base to which the animal still adhered by its suctorial disc was 

 complete. It seems to me that a " hyaline tube," on which the 

 first rows of pellets are said to be deposited, must first be con- 

 structed, and that when these rows are completed it would have 

 to be got rid of in some way, unless the intervening space were 

 filled up by continuing to build upon it downward, which idea 

 was not warranted by my observations. 



The conclusion I am led to is that the first pellet is held in po- 

 sition by a temporary attachment, proceeding from its own body, 

 in some unknown manner, and so situated as not to be in the way 

 when its purpose is accomplished. My theory was produced by 

 observing the singularly beautiful manner in which the tube was 

 brought down. At short intervals the little builder ceased " making 

 bricks," and, suddenly contracting itself upon its adhering tail, 

 pulled the tube down with it for a short distance. By these re- 

 peated contractions and efforts the interval was gradually re- 

 duced, until the connection with the base was made and the work 

 finished. 



We have hitherto been accustomed to account for the tapering 

 construction of the case solely by the different diameters of the 

 body and the tail, but it is possible that a double purpose led to 

 the conception of the design, viz., the lessening of labor in build- 

 ing, and the facilitation of the "pulling-down process" I have de- 

 scribed, which latter is no doubt materially aided thereby. Of 

 course it will be asked why the Melicertian does not solve the dif- 

 ficulty by laying the foundations of its tube upon the base on 

 which it finally rests. I simply reply, I don't know. But I also 

 add that, on October 2d, I had the pleasure of seeing another 

 young Melicertian engaged in building, and I also observed the 

 same interval between the caudal end of the tube and the base. 



