of the Amazons Valley. 103 



able to the recent genus Fossar, near Lacuna^ and to tlie 

 family Littorinicl^. 



4, Hemisinus snlcatus^ Conrad, oj-). cit. pi. 10. fig. 2. 



" An elegant species, closelj allied to H. teneJlus ; but it 

 has a longer last whorl and a narrower aperture." Mr. Conrad 

 considers this shell " a decidedly freshwater genus, a genus 

 living in South- American rivers." 



5. Dyris gracilis^ Conrad, oj). cit. pi. 10. fig. 8. 



Another extremely minute shell (about 3 lines in length) . Mr. 

 Conrad thinks the mouth similar to that of the genus Melania. 



6. Neritina Ortoni, Conrad, oj). cit. pi. 10. fig. 5, 

 Nerilina i^upa ., Gabb,Amer.Journ. Conch, vol. iv. p. 197, pi. 16. 



PL V. figs. 2 «, h. 



I am inclined to regard these two species as probably 

 synonymous. Having received more than 250 specimens, I 

 think it possible to* trace up all the variations between the 

 young and aged specimens, so as to connect them together. 

 The colour-markings are inconstant, and cannot be dealt with, 

 save as indicating varieties ; and the form of the shell varies 

 with the age. 



The Neritince occur both in fresh and brackish waters, two 

 West-Indian species even inhabiting the sea. 



7. Bulimus linteuSj Conrad, op. cit. pi. 10. fig. 9. 



An outline is given of this, the only land-shell in the col- 

 lection. The author refers it to some subgenus of Bulimus^ 

 probably Plectostylusj Beck. 



Odostomia ? PI. V. figs. 4 a, h. 



I venture to think the little shell figured in our plate (fig. 4) 

 is referable to this genus. Odostomia is sometimes found in 

 brackish water. Fig. a is of the natural size ; fig. h the same 

 enlarged. I prefer, however, to await better specimens before 

 describing it further. 



CONCHIFERA. 



Anodon, Cuvier. 



Shell like Unio, but edentulous ; oval, smooth, rather thin, 

 compressed when young, becoming vcntricose with age. 



Anodon Batesii, sp. nov. PI. V. fig. 10. 



I beg permission to dedicate this very beautiful and unique 

 Amazonian Anodon to my friend Ileniy Walter Bates, Secre- 



