Fam. 3. Belemnitidae. Extinct; phragmacone short with ventral siphuncle, prolonged dorsally into long proöstracum; rostrum large and cylindrical. Belemnites, 350 species from Jurassic and Cretaceous. Diploconus, Upper Jurassic.
Fam. 4. Belopteridae. Extinct; rostrum and phragmacone well developed, phragmacone often curved; initial chamber small. Beloptera, Eocene. Bayanoteuthis, Eocene. Spirulirostra, Miocene.
Fam. 5. Spirulidae. Dorsal and ventral sides of posterior extremity of shell uncovered by mantle; no rostrum or proöstracum; shell calcareous, coiled endogastrically and sipnunculated; fins posterior. Spirula, three living species known, abyssal.
Fam. 6. Ommatostrephidae. Shell internal and chitinous, ending aborally in a little narrow cone; tentacular arms short and thick; suckers with denticulate rings. Ommatostrephes, fins aboral, simple and rhomboidal, British. Ctenopteryx, fins pectinate, as long as the body; Bathyteuthis, fins terminal, rudimentary; tentacular arms, filiform; abyssal. Rhynchoteuthis, tentacular arms united to form a beak-shaped appendage. Symplectoteuthis. Tracheloteuthis. Doridicus. Architeuthis; this is the largest of Cephalopoda, reaching 60 ft. in length including arms.
Fam. 7. Thysanoteuthidae. Arms enlarged, bearing two rows of suckers and filaments; fins triangular, extending whole length of body. Thysanoteuthis, Mediterranean.
Fam. 8. Onychoteuthidae. Fins terminal; tentacular arms long; suckers with hooks. Onychoteuthis, hook-bearing suckers on tentacular arms only. Enoploteuthis, hook-bearing suckers on all the arms. Veranya, body very short, tentacular arms atrophied in the adult, Mediterranean. Chaunoteuthis, body elongated, tentacular arms atrophied. Pterygioteuthis. Ancistroteuthis. Abralia. Teleoteuthis. Lepidoteuthis.
Fam. 9. Gonatidae. Body elongated; fins terminal; radula with only two lateral teeth. Gonatus.
Fam. 10. Cheiroteuthidae. Tentacular arms long, not retractile; resisting apparatus well developed. Cheiroteuthis, suckers along the whole length of the tentacular arms. Doratopsis, body very long and slender with aboral spine, dorsal arms very short. Histioteuthis, six dorsal arms united by membrane, photogenous organs present. Histiopsis, membrane of dorsal arms only half-way up the arms, photogenous organs present. Calliteuthis, no brachial membrane, photogenous organs present. Grimalditeuthis, two fins on each bide, no tentacular arms.
Fam. 11. Cranchiidae. Eight normal arms, very short; eyes prominent; fins small and terminal. Cranchia, body short, purse-shaped, normal arms short, fins entirely aboral. Loligopsis, body elongated, conical, tentacular arms slender. Leachia, tentacular arms absent, funnel without a valve. Taonius, body elongated, normal arms, rather short, eyes pedunculated.
| Fig. 38.—Octopodous Cephalopods. |
| A, Pinnoctopus cordiformis, Quoy and Gain (from New Zealand). B, Tremoctopus violaceus, Ver. (from the Mediterranean). C, Cranchia scabra, Owen (from the Atlantic Ocean; one of the Decapoda). D, Cirrhoteuthis Mulleri, Esch. (from the Greenland coast). |