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JOURNAL OF CONCHOI.OGY, VOL. ID, NO. 5, JANUARY, I902. 



and afterwards continued its descent, making in all thirty-nine inches 

 of thread. Numerous individuals fell with very short threads. A few 

 were placed on twigs over water, on reaching which they usually made 

 some sort of attempt to return upon the thread, but fell. The thread 

 of one of these was thirty-four inches long. 



A. isevis. — A full-grown specimen placed on a stick two to three 

 feet from plants on the ground below, soon crawled dff, but fell, after 

 having been suspended ten minutes, just before reaching the plants. 

 The thread was immediately caught up by the breeze and held almost 

 horizontally along by the stick. Other individuals fell without threads. 

 One, which had left its support for a space of half-an-inch, turned, 

 ascended the short thread, and regained its former position. 



Arion ater. — The young fell with three to seven inches of thread; 

 large individuals crawled from supports, but were not supported by 

 their slime. 



A. subfuscus. — This slug, often at- 

 taining a large size, has not been seen by 

 me to make a thread when full-grown. 

 Young and partly-grown individuals, 

 however, readily do so ; and one made a 

 thread 37 inches long. In the case of an 

 individual, i^ inches long, I touched the 

 tentacles with a finger wet with saliva, 

 but the animal still continued to descend; 

 when its thread was seven inches long, 

 however, on my holding a strip of wood 

 so as to cause a shadow to fall on the 

 hinder parts of the body, the slug reversed 

 its position and crept up the thread, 

 finally regaining its footing upon the twig 

 from which it had descended (fig. 5). 

 During the ascent the head was some- 

 times turned a little to the right or to 

 the left. A depression was caused by 

 the thread upon the anterior part of the 

 foot for about a quarter-of-an-inch, but 

 beyond this no trace of it was observable. 

 An accumulation of mucus soon began 

 to appear dorsally at the tail, and gradu- 

 ally increased in size ; it was composed, 

 no doubt, of the slack of the thread, to- 



FlG. 5. 



.1 •,. T -,■.• Id 1 •. 1 An'oii subfuscus ascendiiiEc the 



gether With an additional film deposited thread by which it has suspended itself 



from a twig ; drawn from life by the 

 writer. 



during the ascent ; on the little mass 



