‘440 MISS LETTICE DIGBY ON THE STRUCTURE OF 
Lastly, the pigmented snout, the triangular gill-plumes, so 
characteristic of the Rhachiglossa, the longitudinal fold and the 
other features of the stomach, and the simple pouch-like salivary 
glands, all bring Limnotrochus into close relationship with 
Typhobia. 
Like Ohytra, Limnotrochus has thus obviously scattered 
affinities, and it is more difficult to place than even Chytra itself. 
It is undoubtedly allied both to Chytra and to Typhobia, as weil 
as to the Stromboid group represented by the genera Strombus 
and Aporrhais; and it is perhaps more nearly allied to these 
genera than to any other living types. But, on the other hand, 
it is quite distinct from them all, and must, at any rate for the 
present, be regarded as unique. 
List of Papers cited in the Text. 
1. Bouvier, E. L.—‘‘Systéme Nerveux, Morphologie Générale 
et Classification des Gastéropodes Prosobranches.’’ Annales 
des Sciences Naturelles, Zool. 7° série, pp. 1-510 (1887). 
2. Fiscuer, P.—Manuel de Conchyliologie et de Paléontologie 
Conchyliologique. Paris, 1877. 
3. Hatter, B.—“ Die Morphologie der Prosobranchier.” Mor- 
pholg. Jahrb. vol. xix. pp. 553-589. 
4. Moors, J. E. S.—“ On the Hypothesis that Lake Tanganyika 
represents an old Jurassic Sea.” Qu. Journ. Micr. Sci. 
vol. xli. pp. 803-321. 
5. Moorz, J. E. S.—‘‘ Molluses of the Great African Lakes. 
Part 1V. Wassopsis and Bythoceras.” Qu. Journ. Micr. Sci. 
vol. xli. pp. 187—200. 
6. Moors, J. E. S.—“ Molluscs of the Great African Lakes. 
Part I. Typhobia and Bathanalia.” Qu. Journ. Micr. Sci. 
vol. xli. pp. 181-192. 
7. Ropert, A.—‘‘ Gastéropodes: Le Troque.”  ‘ Zoologie 
Descriptive,’ Paris, vol. ii. pp. 381-415. 
8. Smirnu, E. A.—“On a Collection of Shells from Lakes 
Tanganyika and Nyassa, and other Localities in Hast Africa.” 
Proc. Zool. Soc. 1881, pp. 276-300. 
9. TroscueL, F. H.—‘“ Das Gebiss der Schnecken.” Band i. 
Berlin, 1856-1863. 
