Transactions. 185 



understanding the physiology of this curious mouth. I think that 

 the jaw is used to snip off portions from the edge of the leaf, and by 

 the action of muscles on the cartilage under the ribbon it is 

 drawn to the front of the mouth, turning the teethy sac inside out 

 to rasp portions from the flat side of the leaf, or it may be used to 

 rasp the leaf when held by the jaw. Behind the buccal mass 

 there is a short oesophagus, through which the food passes to the 

 crop, which is used as a store. It then enters the stomach, when 

 after digestion and mixing -nath the secretion from the liver, it 

 passes on to the bowel and the vent, whicli opens externally by 

 the side of the respiratory orifice. ^Yhen examining the con- 

 tents of the bowel I found a great number of small intestinal 

 worms, or entozoa. 



Nenwus 5)t/^/«.— Surrounding the oesophagus is a collar of 

 nerve tissue, which may be called the large nerve centre or brain 

 of the animal. It is divided into two divisions — the siipra- 

 asophageal ganglia ; and the sub-<xsophageal ganglia. Both are 

 united by bands of nerve fibres. The supra-oesophageal ganglia 

 (which in some measure corresponds to the cerebrum of the higher 

 animals) give off the principal nerves to the head segment, eyes, 

 &c., the first pair going to the inferior antenna^. We know that 

 in the higher animals the first pair are the special nerves of the 

 sense of smell, and if we reason here by analogy we will call the 

 smaller antenna the organs of smell. The second pair are the 

 optic nerves. The third supplies the retractor muscles of the eye, 

 a branch going to the retractor of the head. The sub-cesophageal 

 ganglia are divided into two portions— an anterior and posterior 

 portion, the anterior giving nerves to the muscular substance 

 of the foot, &c. The posterior gives branches to the body wall, 

 viscera, &c. The beautiful silvery appearance of the nerves radi- 

 ating from the large nerve centre is very striking, and when once 

 seen is never forgotten. 



Generative Orga7is.—^\\\?. slug, like many members of this 

 order, is hermaphrodite, i.e. it is both male and female, but not 

 self imjjregnating. The common orifice is under the fold of the 

 mantle in front of the vent. The organs consist of vagina ; vaginal 

 prostate; receptaculum seminis ; albuminiparous gland ; penis sac; vas 

 deferenes ; hermaphrodite gland, with its duct. The principal oro-an 

 is the gland, which is situated in the left lobe of the liver. * It 

 consists of numerous follicles of a darkish colour, held together by 

 connective tissue. The ova and spermatosoa are both formed in 



