Palaeos		Paragastropoda
Mollusca		Paragastropoda

Paragastropoda

CONCHIFERA
`==Helcionelloida
   `--+--PARAGASTROPODA
      |  |--Pelagiellida
      |  `--Mimospirida
      |     |--Onychochilidae  
      |     `--+--Cliospiridae  
      |        `-?Omphallocirridae  
      `--+--Bellerophontoidea (torted)
         `--GASTROPODA (crown group) 

These strange Devonian snail-like molluscs do not seem to have any clear relations. The distinctive frills would presumably be for the inhalent siphon, and the animal was most likely sedentary, probably a filter feeder. Knight, et al., 1960 placed them in the Macluritidae (gastropods), although they lived in the Devonian, long after the last Macluritids died out. Linsley and Kier 1984 considered them members of the Euomphaloid paragastropods. Flow-tank studies by Morris (1991) indicate they would seem to be untorted, but muscle scars are ambigious [Wagner 2001]. I have tentatively left them in the Gastropoda, but I acknowledge they may equally belong among the Paragastropoda.