314 THE ZOOLOGIST. 



helping to keep the animal at the surface. Notwithstanding 

 Bang's remark that the thread is doubtless formed of a special 

 secretion, Eydoux and Souleyet think it probable that it consists 

 merely of locomotory mucus, which, in these molluscs, may 

 possibly possess special characters. Bang, it may be added, 

 while examining spirit specimens, found, under the foot, a little 

 glairy mass, which attached itself to the point of the scalpel, and 

 was easily drawn out into a thread a foot and a half long ; each 

 specimen presented the same peculiarity, and Bang concluded 

 that this was the substance from which the thread is made ; it 

 seems more probable, however, that the little masses were the 

 remains of threads already spun, and perhaps reascended by the 

 animal. 



The above, the present writer believes, is all that is known of 

 the spinning habits of Litiopa. These habits are certainly of a 

 surprising character : the length of the apparently rapidly made 

 thread, the animal's security upon it, and the facts that it can 

 produce and afterwards ascend by it, not only in its native 

 element, but also in the air, are points of special interest. As 

 to the statements in the books, one may quote, for example, from 

 Johnston's * Introduction to Conchology': — 



" The habits of the Litiopa are not less worthy of your notice. This is 

 a small Snail, born amid the gulf-weed, where it is destined to pass the 

 whole of its life. The foot, though rather narrow and short, is of the usual 

 character, and, having no extra hold, the Snail is apt to be swept off its 

 weed ; but the accident is provided against, for the creature, like a Spider, 

 spins a thread of the viscous fluid that exudes from the foot to check its 

 downward fall, and enable it to regain the pristine site. But suppose the 

 shock has severed their connexion, or that the Litiopa finds it necessary 

 to remove, from a deficiency of food, to a richer pasture, the thread is still 

 made available to recovery or removal. In its fall, accidental or purposed, 

 an air-bubble is emitted, probably from the branchial cavity, which rises 

 slowly through the water, and as the Snail has enveloped it with its slime, 

 this is drawn out into threads as the bubble ascends; and now, having 

 a buoy and ladder whereon to climb to the surface, it waits suspended 

 until that bubble comes into contact with the weeds that everywhere float 

 around!"* 



* Johnston, ' Introduction to Conchology,' 1850, p, 134 ; with references 

 to Rang and Kiener. 



