| It is not uncommon for both Recent and fossil volutes from southern South America to have a protoconch that is corroded to various degrees by cold acidic waters. |
| This protoconch is discoidal or almost dicoidal and sinistral. |
| The protoconch is paucispiral or multispiral, and is smooth except for a few axial riblets near the junction with the teleoconch. |
| The latter species has a smooth, valvatiform, dextrally coiled teleoconch and a sinistral, anastrophic protoconch. |
| These gastropods have slender, high-spired, multiwhorled shells bearing a sinistral protoconch and were united by Knight in the family Streptacididae. |
| On the dorsal portion of the rostral face, the shell layers extend ventrolaterally from those of the protoconch. |
