VI THE NAUTILUS. 



. 



Shells and Mastodon . . . . . . 34, 55, 100 



Sigaretus oldroydii, notes on . . . . .85 



Stepbanoda Iheringi Ancey, n. sp. . . . . .17 



Stephanoda latastei Ancey, n. sp. . . . . .17 



Strobilops liubbardi stevensoni Pilsbry, n. var. . . .46 



Stroinbus, attempt to define the natural groups of . 76, 93 

 Thomson, John H. (Biographical note) .... 113 



Thysanophora hornii Gabb ....... 98 



Tres Marias Islands, Mexico, Natural History of . . 19 

 Turritellidiv, Viviparous Miocene . . . . .68 



Unios of the Sabine River 79 



Unionida? in a tunnel ........ 130 



Unio conjugans Wright, n. sp. . . . . . .89 



Unio Danielsii Wright, n. sp 31 



Unio dispalans Wright, n. sp 50 



Unio Hagleri Frierson, n. sp. (Plate 11.) .... 109 



Unio Harperi Wright, n. sp 6 



Unio Kingii Wright, n. sp. . . . . . . .138 



Unio polymorphic Wright, n. sp. . . . . 42 



Unio rotulatus Wright, n. sp. . . . . . .22 



Unio (Lampsilis) Rovirosai Pilsbry, n. sp. . . .140 



Unio singularis A\ r right, n. sp. . . . . . .75 



Unio Tinker! Wright, n. sp 7 



Unio unicostatus Wright, n. sp 69 



Veronicella, notes on Jamaican . . . . . .131 



Viviparous miocene Turritellidae . . . . .68 



Zonitidre collected by J. H. Ferriss in Arkansas and the 

 Choctaw Nation ..... . 107 



Zunitoides neornexicanus Cockerell A: Pilsbry, n. sp. . . 114 



