OF CONCHOLOGY. 



191 



& Fr. W. Shells, p. 281, fig. 502 ; p. 290, fig. 521.) The lin- 

 gual membrane might have had the centrals and laterals actually 

 existing in the species, but the marginal teeth would have Deen 

 replaced by oblique rows of simple thorn-shaped teeth. (See 

 Ibid., p. 286, fig. 512 ; p. 290, fig. 521.) 



Our figure 4 shows one central and one lateral tooth on the 

 right of the membrane. Figure 3 shows three marginals on the 

 opposite side of the membrane. 



Since the above was written we have seen a living specimen of 

 the species, and find no caudal mucus pore. 



Explanation of Plate 17. 



Figure 1. Amphibulima patula. Centrals and laterals. 



Figure 2. The same. Marginals. 



Figure 8. Helix Newberryana. Marginals from the left of 

 the median line. 



Figure 4. The same. One central and one lateral, the latter 

 from the right of the central line. 



Figure 5. Blandiella reclusa. 



Figure 6. Nanina Calias. The central, first two laterals, one 

 intermediate tooth, and three extreme marginals. 



Figure 7. G-eomelania. The central tooth. 



Figure 8. Same as fig. 6, taken from another portion of the 

 membrane. 



Figure 9. Macroceramus Grossei. A lateral tooth. 



Figure 10. Greomelania. Same as fig. 7. 



Figure 11. Same as fig. 9. A group of centrals and laterals. 



Figure 12, Same as last. An extreme marginal. 



