Shell covered by mantle, or absent; anterior tentacles form a frontal veil; mantle contains spicules.
C. rothschildi also has a large frontal horn and white legs, but the spots in the bulls are very dark and those of the females jagged.
The union of the index and middle fingers by means of a web extending as far as the terminal joints is the distinctive feature of the siamang, which is the largest of the group, and black in colour with a white frontal band.
Shell external and conical; anterior tentacles form a frontal veil; ctenidium extending only over right side; a distinct osphradium.
The acrembolic proboscis or frontal introvert of the Nemertine worms has a complete range.