MELICERTA RINGENS. 9o 



mould, which is a muscular organ, and capable of 

 secreting a waterproof cement, by whicli tliey ai*e 

 fastened together. The result is, not to produce 

 anything like the tubes made by the caddis-worms 

 out of grains of sand, but entirely to cliange the 

 appearance of the materials employed. All lai'ge 

 particles are rejected, and only those retained which 

 will form a homogeneous pulp with the viscid se- 

 cretion; and when the process is complete the head 

 of the creature is bent down, and the pellet de- 

 posited in its appropriate place. Each pellet appears 

 originally to possess a more or less conical figure, 

 but when tliey are squeezed together to make a 

 compact wall they all tend to a hexagonal form, 

 by which they are able to touch at all points, and 

 any holes or interstices are avoided. 



According to Professor Williamson the young 

 Melicerta commences her house by secreting^'a thin 

 hyaline cylinder," and the first row of pellets are 

 deposited, not at the base as would be expected, 

 but in a ring about the middle of the tube. "At 

 first new additions are made to both extremities of 

 the enlarging ring; but the jerking constrictions uf 

 the animal at length force the caudal end of the 

 cylinder down upon the leaf, to which it becomes 

 securely cemented by the same viscous secretion as 

 causes the little spheres to cohere." 



Round the margins of the lobes or expansions 



