Figure 1 in The evolutionary and biomechanical implications of snout and proboscis morphology in Caenogastropoda (Mollusca: Gastropoda)

Figure 1. Schematic classification of proboscis and snout morphology, with retractor muscles shown in grey. (A) Snout; (B) acrembolic proboscis everted; (C) acrembolic proboscis introverted; (D) pleurembolic proboscis everted; (E) pleurembolic proboscis introverted; (F) intraembolic proboscis extended; (G) intraembolic proboscis retracted; (H) polyembolic proboscis everted; (I) polyembolic proboscis introverted; (J) "argobucciniform" proboscis extended; (K) "argobucciniform" proboscis retracted. A–E modified from Fretter and Graham (1994, Figure 88); F–I modified from Miller (1989, Figure 3); J–K modified from Day (1969, Figure 1).