fit PROCEEDINGS OF THE MALACOLOGICAL SOCIETY. 



The Turritellidae are undoubtedly, as maintained by Bouvier [1], 

 closely approximated to the Cerithiiclse. The nervous system of 

 T. communis, Risso, presents points of agreement with that of 

 Ceratoptilus [1] (p. 14G, pi. viii, fig. 33 j in some respects, and with 

 Telescopium [1J (p. 145, pi. viii, fig. 32) in others. _ That is, it 

 resembles the nervous system of the zygoneurous Cerithiidse more 

 nearly than that of any other prosobranch. There are other points 

 of structural similarity between Cerithium and Turritella besides 

 those of the nervous system, as, for instance, the peculiar form of 

 the gill and the elongate osphradiuni. Turritella, though in no 

 way particularly specialized, can scarcely be regarded as approaching 

 a primitive type; it certainly presents a few characters that may be 

 considered somewhat primitive, as, for example, the presence of an 

 epipodium, also the peculiar papillae and fringe of the mantle, and, in 

 the case of T. rosea, Quoy & Gaim., the presence of otoconia; yet, 

 taken on the whole, and especially with reference to the nervous 

 system, we must look upon Turritella as a moderately highly organized 

 monotocardian, and presenting no approach to the structure of the 

 Diotocardia. If the notched forms of Turritella are, as is supposed, 

 allied to the extinct genus Murcliisonia, they will have to be removed 

 from the family Turritellidae. Before this point can be cleared up, 

 however, we must have some knowledge of the anatomy of these forms. 



BIBLIOGRAPHY. 



1. Bouvier, F. L. : Systeme nerveux des Prosobranchs : Ann. Sci. 



Nat., Zool. ser. vn, torn, iii (1887), pp. 145-6, 200. 



2. Clarice, W. : A History of the British Marine Testaceous Molluscs, 



1855, pp. 331, 333. 



3. Fischer, P.: Manuel de Conchyliologie, 1887, pp. 693-4. 



4. Hutton, F. W. : Notes on some Branchiate Gastropoda : Trans. 



New Zealand Inst., vol. xv (1882), p. 122, pi. xiv, fig. c. 



5. Krause, A. : Ein Beitrag zur Kenntniss der Mollusken- Fauna 



des Beringsmeeres : Archiv fur Naturgesch., Bd. li (1885), 

 p. 271, pi. xvii, fig. 3. 



6. Lorcn, S.L.: Ofversigt K. Vetensk. Akad. Forhandl., 1847, p. 194, 



pi. iv. 



7. Moore, J. F. S. : The Molluscs of the Great African Lakes : 



Quart. Journ. Micro. Sci., vol. xlii (1899), pp. 151 and 182. 



8. Sars, G. 0. : Mollusca regionis Arcticoe Novegiae, 1878, pp. 185-6, 



pi. vii, figs. 1 and 2. 



9. Troscliel, F. H. : Das Gebiss der Schnecken, Bd. i, p. 153, pi. xii, 



figs. 11-13. 

 10. Jhering, H. von: Beitrag zur Kenntniss des Nervensystems der 

 Amphineurcn und Arthrocochliden : Morph. Jahr'b., Bd. iii 

 (1877), pp. 166-8. 



