siphonated

Had there been strong prepossessions against the progressive theory, it would probably have been argued that when these cephalopods abounded, and the siphonated gasteropods were absent, a higher order of zoophagous mollusca discharged the functions afterwards performed by an inferior order in the Secondary, Tertiary, and Post-Tertiary seas.

The Antiquity of Man Charles Lyell 1836

I soon became aware of the force of this rule in the class mollusca, when I first attempted to calculate the numerical proportion of Recent species in the Newer Pliocene formations as compared to the Older Pliocene, and of them again as contrasted with the Miocene; for it appeared invariably that a greater number of the lamellibranchs could be identified with living species than of the gasteropods, and of these last a greater number in the lower division, that of entire-mouthed univalves, than in that of the siphonated.

The Antiquity of Man Charles Lyell 1836