A. Eurystomata

A Eurystomata. Oral aperture large, occupying the whole of the oral extremity of the body.

1. Beroidae. The paragastric canals opening into a circum-oral ring. No tentacles. Ex. Beroe, Idyia.

B. Stenostomata

B Stenostomata. Mouth small and narrow.

2. Saccatae. No circum-oral canal; tentacles two. Ex. Pleurobrachia, Eschscholtzia, Hormiphora.

3. Lobatae. Body furnished with a pair of wing-like oral extensions or lobes. Ex. Bolina, Mnemia, Eucharis, Lesueuria.

4. Taniatae. Body ribbon-like; no oral lobes; two tentacles.

Ex. Cestum.