WATSON : ANATOMY OF OOHTHEPHILA. 287 



opening of the oesophagus, and are joined to the cerebral ganglia 

 by long connectives. Like the latter ganglia, they do not appear to 

 present any unusual features. 



The ventral ganglia are joined to the cerebral ganglia by cerebro- 

 pedal and cerebral-pleural connectives of moderate length, and form 

 a compact group which is more nearly symmetrical in appearance 

 than is usually the case. The ventral group consists of a pair of 

 rounded pedal ganglia in front, and close behind them what at first 

 sight seems to be a single pair of pleuro-visceral ganglia. This 

 appearance is due to the right parietal ganglion being completely 

 fused with the right pleural ganglion, and the left parietal com- 

 pletely fused with the abdominal ganglion on one side and almost 

 completely with the left pleural ganglion on the other. 



The otocysts are situated on the ventral surface of the pedal 

 ganglia, near their posterior ends. Each otocyst contains a number 

 of oval otoconia, with deeply staining centres. The otoconia vary 

 considerably in size, but many of them, attain a maximum diameter 

 of "01 mm. 



The distribution of the various nerves does not seem to exhibit 

 any marked difference from that usually found in the Helicidse ; 

 but time has not permitted the detailed examination of the smaller 

 nerves and arteries of this species, structures which could be better 

 studied in some larger member of the genus. 



The Digestive System. — -The jaw measures about '16 mm. in 

 breadth ; it is of a rather light brown colour, and is crossed by 

 twelve to fourteen broad vertical ribs, as shown in Fig. 7 on 

 Plate VI. 



The radula is rather narrow, measuring about l"9mm.X'6mm. 

 when flattened out. The transverse rows of teeth are nearly straight, 

 though they trend slightly forwards in the region of the outer 

 marginal teeth, and to a less extent also in the region of the inner 

 lateral teeth. The central teeth are tricuspid, having a small ectocone 

 on each side of the mesocone. The lateral teeth are bicuspid, there 

 being a short ectocone in addition to the much larger mesocone, 

 which, however, is shorter than the basal plate. The endocone is 

 represented by a sm.all flange on the inner side of the mesocone, 

 to which it is wholly united. In the transitional teeth the distal 

 end of the endocone becomes separated from the mesocone, and the 

 ectocone is not so short. In the marginal teeth the endocone is more 

 prominent, and is only united with the mesocone for about half its 

 length ; while the ectocone is usually divided into two small cusps, 

 or even into three in one or two of the teeth. The marginal teeth 

 are niuch shorter than the others, especially near the edges of the 

 radula ; but the forms of the teeth will be seen from Fig. 8 on 

 Plate VI. The following are the radular form ulse of two specimens 

 examined: (14+9+1+10+14) X ll6 ; (14+10+1+11+14) xllO. 



The extremity of the radula-sac projects as a small papilla laeyond 



