188 J. B. S. MOORE. 



another (fig. 35^ IJi), and thus approximate to the primitive 

 type of pedal nerves possessed by the Helicinidae. The pedal 

 ganglia themselves are united together by a great transverse 

 commissure (fig. 35) which contains ganglionic cells ; and on 

 their postero-lateral surfaces they give off four or five large 

 nerves which pass into the foot. The pedal ganglia are con- 

 nected with the cerebral, and the pleural ganglia by the cerebro- 

 pedal and pleuro-pedal connectives already described. 



The otocysts of the Typhobias are relatively immense, and 

 each is innervated by two fine nerves springing from the upper 

 portion of the cerebral ganglia (fig. 35, 6). The position 

 occupied by the otocysts is very anomalous, being completely 

 above and separated from the pedal ganglia, close to the cerebro- 

 pleural ganglionic mass (fig. 35, 10). The otoliths are numerous 

 and small (fig. 36), and the otocyst is lined by a well-marked 

 sensory epithelium, from the free internal surfaces of the cells 

 composing which there are given off" fine " sensory processes " 

 projecting into the cavity of the sac (fig. 36, 1). The posi- 

 tion and character of the otocysts, and the prolonged pedal 

 ganglia, are features in keeping with the generally primitive 

 characters which the other parts of the nervous system seem to 

 possess. 



The digestive system presents points which, like those 

 appertaining to the nerves, are at once interesting and new. 

 The buccal mass is exceedingly small, and the radular sac is 

 very short. There are no horny jaws, and the radular dentition 

 is unique and peculiar in the extreme. A single transverse 

 row of teeth is represented in fig. 43 ; also in the upper figure 

 on page 189. The salivary glands are long and branched, the 

 oesophagus being long, slender, and longitudinally folded. In- 

 ternally it is lined by ciliated and glandular cells. Posteriorly 

 the oesoph agus opens into the right side of the stomach, which 

 is divided into an anterior and posterior chamber, the oesophagus 

 opening into the latter. This posterior chamber of the stomach 

 is traversed by several marked folds, the most conspicuous of 

 which extends longitudinally (fig. 44, 7). On the floor of the 

 stomach, to the right of this fold, are found the openings of the 



