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FAMILY 1.-ARGONAUTIDÆ. “Paper Nautilus.” (1 Genus,
4 Species). DISTRIBUTION.-Open seas of all warm regions. Two species fossil in Tertiary deposits.
FAMILY 2.—OCTOPODIDÆ. “ Polypi.” (7 Genera, 60
Species). DISTRIBUTION.—Norway to New Zealand, all tropical and temperate seas and coasts.
FAMILY 3.—TEUTHIDÆ. “Squids or Sea-pens." (16 Genera,
102 Species.) DISTRIBUTION.—Universal, to Greenland ; 2 other genera are fossil, in the Lias and Oolite.
FAMILY 4.-SEPIADÆ. “Cuttle Fish.” (1 Genus, 30 Species).
DISTRIBUTION.—All seas : 4 other genera are fossil, in Eocene and Miocene deposits.
FAMILY 5.-SPIRULIDÆ. (1 Genus, 3 Species). DISTRIBUTION.—All the warmer seas.
FAMILY 6. — BELEMNITIDÆ. Fossil (6 Genera, 100
Species). DISTRIBUTION.—Lias to Chalk in Europe, India and North America.
FAMILY 7.-NAUTILIDÆ. · (1 Genus, 3 Species, Living; 4
Genera, 300 Species, Fossil).
DISTRIBUTION.—Indian and Pacific Oceans; and the fossil species from the Silurian Period to the Tertiary, in all parts of the world.
(8 Genera, 400
DISTRIBUTION.- Lower Silurian to Lias.
FAMILY 9.-AMMONITIDÆ. Fossil. (14 Genera, 1100
Species). DISTRIBUTION.–Upper Silurian to Chalk. Found at 16,000 feet elevation in the Himalayas.
FAMILY 1.-STROMBIDÆ. (4 Genera, 86 Species.)
DISTRIBUTION.—The Strombidæ, or Wing-shells, inhabit tropical and warm seas from the Mediterranean to New Zealand ; most abundant in the Indian and Pacific Oceans. There are nearly 200 fossil species, from the Lias to Miocene and recent deposits.
FAMILY 2.-MURICIDÆ. (12 Genera, 1000 Species.)
DISTRIBUTION.—All seas, most abundant in the Tropics. Trichotropis is confined to Northern seas; Murex and Fusus are cosmopolitan. There are about 700 fossil species, ranging from the Oolite to the Miocene and recent formations.
FAMILY 3.-BUCCINIDÆ. (24 Genera, 1100 Species.)
DISTRIBUTION.—The Buccinidæ, or “ Whelks,” range over the whole world, but some of the genera are restricted. Buccinum inhabits the north and south temperate seas; Monoceros the West Coast of America; Cassidaria the Mediterranean; Phos, Harpa, Eburna, and Ricinula, are confined to the Pacific; Dolium inhabits the Mediterranean as well as the Pacific. There are about 350 fossil species, mostly from the Eocene and Miocene beds.
FAMILY 4.-CONIDÆ. (3 Genera, 850 Species.)
DISTRIBUTION.—The Cones are universally distributed, but this applies only to the genus Pleurotoma. Conus is tropical and sub-tropical, and Cithara is confined to the Philippine Islands. There are about 460 fossil species, from the Chalk formation to the most recent deposits.
FAMILY 5.-VOLUTIDÆ (5 Genera, 670 Species.)
DISTRIBUTION.—The Volutes are mostly tropical; but a small species of Mitra is found at Greenland, and a Marginella in the Mediterranean. Cymba is confined to the West Coast of Africa and Portugal. Voluta extends south to Cape Horn. There are about 200 fossil species, from the Chalk and Eocene to recent formations.
FAMILY 6.-CYPRÆIDÆ. (3 Genera, 200 Species.)
DISTRIBUTION.—The well-known Cowries are found all over the world, but they are much more abundant in warm regions. One small species extends to Greenland. There are nearly 100 fossil species, from the Chalk to the Miocene and recent formations.
FAMILY 7.-NATICIDÆ. (5 Genera, 270 species.)
DISTRIBUTION.—The Naticidæ, or Sea-snails, though most abundant in the Tropics, are found also in temperate seas, and far into the Arctic regions. Two other genera are fossil; and there are about 300 extinct species, ranging from the Devonian to the Pliocene formations.
FAMILY 8.-PYRAMIDELLIDÆ (10 Genera, 220 Species.)
DISTRIBUTION.-These turreted shells are very widely distributed both in temperate and tropical seas; and most of the genera have also a wide range. There are about 400 extinct species, from so far back as the Lower Silurian to the Pliocene formations.
FAMILY 9.-CERITHIADÆ. (5 Genera, 190 Species.) DISTRIBUTION.—These are marine, estuary, or fresh-water shells, of an elongated spiral form; they have a world-wide distribution, but are most abundant in the Tropics. Potamides (41 sp.), is the only fresh-water genus, and is found in the rivers of Africa, India and China, to North Australia and California. Another genus is exclusively fossil, and there are about 800 extinct species, ranging from the Trias to the Eocene and recent formations.
FAMILY 10.-MELANIADÆ. (3 Genera, 410 Species.)
DISTRIBUTION.Fresh-water only: lakes and rivers in warm countries, widely scattered. South Palæarctic and Australian regions, from Spain to New Zealand ; South Africa, West Africa, and Madagascar; United States. There are about 50 fossil species, from the Wealden and Eocene to recent formations,
FAMILY 11.-TURRITELLIDÆ. (5 Genera, 230 Species.)
DISTRIBUTION.- Universal. Cæcum is found in north temperate seas only. The other genera are mostly tropical, but some species reach Iceland and Greenland. There are near 300 species fossil, ranging from the Neocomian to the Pliocene formations.