Sentence:  In Ancistrotheutis the attachment ring persists, and the hook sac surrounding the tentacle hook is closed except during function contrary to the condition in the <WSD>armhooks</WSD> where the hook always projects from the sac. 
Meaning of the word marked with <WSD> tags:  A hook-like projection on the arm of a cephalopod, such as on the armhook squid (Gonatus fabricii).