THE ANATOMY AND SYSTEMATICS OF CERATOXANCUS, A GENUS OF DEEP-WATER PTYCHATRACTINAE (GASTROPODA, TURBINELLIDAE) WITH LABRAL SPINE

The anatomy of Ceratoxancus is characterized by a short or very short proboscis, the presence of an accessory salivary gland, the ventral od ontophoral retractor passing through the nerve ring, and the position of the buccal mass at the proboscis base in contracted condition. Thes e characters are shared by other representatives of the subfamily and confirm the classification of Ceratoxancus in the Ptychatractinae, unt il now based on shell and radula characters. Ceratoxancus Kuroda, 1952 , comprises six species of which four are described as new from the Ne w Caledonia region in deep water (530-830 m). Ceratoxancus elongatus S akurai, 1958, is removed from the synonymy of C. teramachii Kuroda, 19 52, and both species are recorded from the southwest Pacific. Species of Ceratoxancus with a long labral spine present numerous shell breaka ges, while toothless species have much fewer scars, and it is hypothes ized that the tooth and outer lip are used in prey capture with accomp anying shell breakage.