202 J. E. S. MOOEE. 



Typhobias are self-contained, and have undoubtedly under- 

 gone individual specialisation of their own. It will there- 

 fore be most expedient, most natural, and most expressive of 

 the actual anatomical facts, to separate these two genera of 

 Typhobias as a family by themselves, the members of which 

 have affinities with, and stand in the relation of fore- 

 runners of, those more modern forms which group them- 

 selves about the Strombidse. They have been seen also to 

 exhibit more or fewer of the characters of a wider range of 

 forms, more especially of the Aporrhaidse, Xenophoridse, 

 Cyprseidse, and that ill-defined group the Ptenoglossa. 



For this family I propose the name Typhobiidse; Ty phobia 

 Horei and Bathanalia Howesi represent the two generic 

 forms at present known. 



The Typhobias are intensely interesting forms ; their 

 affinities show that they have without doubt been cut off 

 from an exclusively marine stock at what is, geologically 

 speaking, no very remote period of time. 



DESCRIPTION OF PLATES 11—14, 



Illustrating Mr. J. E. S. Moore's paper on '' The Molluscs 

 of the Great African Lakes.^' 



PLATE 11. 



Fig. 1. — Living Typliobia. 1. Tentacles. 2. Eyes. 3. Operculum. 



Fig. 2. — Animal removed from shell. 1. Anterior, 2. Posterior siphon. 

 3. Embryos seen through the thin wall of the ovisac. 4. Stomach. 5. Ovary. 

 6. Liver. 7. Anus. 8. Gills. 



Fig. 3. — Interior of the mantle cavity. 1. Siphon. 2. Anus. 3. Genital 

 aperture. 4. Ovisac. 5. Heart. 6. Kidney. 7. Gills. 8. Osphradium. 

 9. Muscles of mantle vrall. 



Fig. 4. — Mantle cavity of Melania, species ? from Philippine Islands. 

 1. Siphon. 2. Gills. 3. Osphradium. 



Fig. 5. — Nervous system of Typhobia Horei dissected from above. 

 1. Buccal ganglion. 2. Buccal mass. 3. Tentacular nerve. 4. Pedal 



