INDEX 



TO 



THE NAUTILUS, VOL. XXI. 



INDEX TO SUBJECTS, GENERA AND SPECIES. 



Acmsea alveus Conrad ..... 



Acmaea testudinalis Mull. ...... 1 



Acmsea, New England species of, (PI. II) . . 1, 24 



Acuminia Dall, n. subgen. of Terebra . . . 124, 125 



Aclelopoma stolli Martens . . . . . . .78 



Alabama, Eocene fossils from ...... 8 



Alaska, U. S. Coast Survey Expedition in the year 1867 . 29 

 Ampullaria, the origin of the lung . . . . .11 



Ancey collection of shells . . . 59 



Anculosse, On certain immature . . . . . .110 



Anculosa praerosa Say (PI. X, figs. 1-6) . . . .111 



Anculosa subglobosa Say (PI. X, figs. 9-11) . . .114 

 Anculosa tintinnabulum Lea. (PI. X, figs. 7-8) . . . 115 

 Ancylidae, New species of (PL IX) .... 126,136 



Ancylus hemisphsericus Walker, n. sp. (PL IX, figs. 14-16). 140 

 Ancylus hendersoni Walker, n. sp. (PI. IX, figs. 8-10) . 138 

 Ancylus hinkleyi Walker, n. sp. (PI. IX, figs. 11-13) . . 139 

 Ancylus novanglise Walker, n. sp. (PL IX, figs. 5-7) . . 138 

 Anodon moretonianus Sowb. ...... 50 



Ashmunella rhyssa hyporhyssa Ckll. . . . . .11 



Australian Unionidae, Notes on . . . . . .118 



(iii) 



