WOODWARD : ANATOMY OF VOLUTA, ETC. 123 



forms, and from what we know in this respect the Volutidoa and 

 Mitridae have no connection. Neither should I myself consider that 

 there was any similarity between the radulae ; the only Volute which 

 in its radula suggests the Mitridae is the genus Volutolijria, and from 

 the character of the tooth I should conclude that it had little in common 

 with the forms at present placed in the genus Voluta. Personally, 

 with regard to the radula of Volutilithes, I would lay stress on the 

 central tooth, which is undoubtedly volutoid, whereas the lateral teeth 

 suggest that they are undergoing reduction, a feature which we might 

 expect to see preserved in a primitive Volute. If we may compare 

 this radula with that of any typical living rhachiglossate, I would 

 suggest a resemblance to the Turbinellidse and Buccinidae. 



The nervous system. — Owing to the excellent state of preservation 

 of the specimens it was possible to work out the nervous system of 

 Volutilithes, in spite of its small size, in much greater detail and with 

 better results than in the very much larger Voluta. The arrangement 

 of the ganglia constituting the nerve-collar in the two genera is, 

 however, practically identical, as a comparison of Figs. 9 and 10 will 

 show. It was, moreover, possible to demonstrate the dialyneurous 

 condition on the left side, which was only surmised to be present in 

 Voluta. The otocyst also was easily seen, and even the tine nerve 

 connecting it with the cerebral ganglion (Fig. 12). As in other 

 Rhachiglossa, a single large otolith was found within this structure. 



Conclusion-. 



A comparison of the above accounts will show, I think, that while 

 the three forms dealt with differ in some features in their anatomy, 

 yet they so closely resemble one another in so many other points that 

 we are justified in retaining them in one family. Volutilithes, the 

 shell of which has long been known, was originally placed in the 

 family Volutidae on purely conchological grounds. On the other 

 hand, the animal of Neptuneopsis was examined at the same time 

 as the shell, and I think if it had not been for a consideration of the 

 radula, and possibly also of other anatomical features, there would 

 have been more hesitation in placing this form in the Volutida3, since 

 the only volutoid character seen in the shell is the protoconch, 

 whereas the general form of the shell and the absence of characteristic 

 folds on the columella and the presence of a large operculum would 

 have told strongly against its volutoid affinities. Nevertheless, an 

 examination of its anatomy, especially of its nervous system, alimentary 

 canal, with the radula and appended glands, and the pallial complex, 

 shows that this form is undoubtedly a near ally of the genus Voluta. 



Volutilithes, though unhesitatingly placed with the Volutidae on 

 conchological grounds, differs from the family more than Neptuneopsis 

 does, and whilst from the peculiar character of its salivary glands 

 and the details of its nervous system we should certainly regard it 

 as belonging to that family, yet in the character of its radula, the 

 small size and nature of the oesophageal caecum, and the absence of 



