i think dolphins are in the families delphinidae and Platanistoidea. the killer whale, the pigmy killer whale and the false killer whale all fall under the family delphinidae. technically it's not the genus but rather the family which branches into the different geni [genuses?]. hope that was some help

Whales, dolphins, and porpoises are in the 'Order' Cetaceae, but in different 'Families'.

1) The order "Cetacea" has 3 suborders: - Mysticeti (Baleen whales) - Odontoceti (toothed whales) - Archaeoceti (extinct) Broadly speaking, all those animals can be considered as members of "whales" suborders, or of the "whales" order. The word "dolphin" can have various definitions. In this article, a "dolphin" is any member of the families Delphinidae and Platanistoidea (oceanic and river dolphins)(families of Odontoceti). "Six species in the family Delphinidae are commonly called "whales" but are strictly speaking dolphins." Further information: http://en.wikipedia.org/wiki/Cetacea http://en.wikipedia.org/wiki/Odontoceti 2) dolphins: "Dolphins are aquatic mammals that are closely related to whales and porpoises. There are almost forty species of dolphin in seventeen genera. They vary in size from 1.2 metres (4 ft) and 40 kilograms (88 lb) (Maui's Dolphin), up to 9.5 m (30 ft) and ten tonnes (the Orca or Killer Whale). They are found worldwide, mostly in the shallower seas of the continental shelves, and are carnivores, mostly eating fish and squid. The family Delphinidae is the largest in the Cetacea, and relatively recent: dolphins evolved about ten million years ago, during the Miocene. Dolphins are considered to be amongst the most intelligent of animals and their often friendly appearance and seemingly playful attitude have made them popular in human culture." "The word [dolphin] is used in a few different ways. It can mean: - Any member of the family Delphinidae (oceanic dolphins), - Any member of the families Delphinidae and Platanistoidea (oceanic and river dolphins), - Any member of the suborder Odontoceti (toothed whales; these include the above families and some others), - Used casually as a synonym for Bottlenose Dolphin, the most common and familiar species of dolphin. In this article, the second definition is used. Porpoises (suborder Odontoceti, family Phocoenidae) are thus not dolphins in this sense. Orcas and some closely related species belong to the Delphinidae family and therefore qualify as dolphins, even though they are called whales in common language." "Kingdom: Animalia Phylum: Chordata Class: Mammalia Order: Cetacea Suborder: Odontoceti Family: Delphinidae and Platanistoidea (Gray, 1821) Genera: See article below." "- Family Delphinidae, oceanic dolphins Genus Delphinus Long-Beaked Common Dolphin, Delphinus capensis Short-Beaked Common Dolphin, Delphinus delphis Genus Tursiops Bottlenose Dolphin, Tursiops truncatus Indo-Pacific Bottlenose Dolphin, Tursiops aduncus Genus Lissodelphis Northern Rightwhale Dolphin, Lissodelphis borealis Southern Rightwhale Dolphin, Lissiodelphis peronii Genus Sotalia Tucuxi, Sotalia fluviatilis Genus Sousa Indo-Pacific Hump-backed Dolphin, Sousa chinensis Chinese White Dolphin (the Chinese variant), Sousa chinensis chinensis Atlantic Humpbacked Dolphin, Sousa teuszii Genus Stenella Atlantic Spotted Dolphin, Stenella frontalis Clymene Dolphin, Stenella clymene Pantropical Spotted Dolphin, Stenella attenuata Spinner Dolphin, Stenella longirostris Striped Dolphin, Stenella coeruleoalba Genus Steno Rough-Toothed Dolphin, Steno bredanensis Genus Cephalorynchus Chilean Dolphin, Cephalorhynchus eutropia Commerson's Dolphin, Cephalorhynchus commersonii Heaviside's Dolphin, Cephalorhynchus heavisidii Hector's Dolphin, Cephalorhynchus hectori Genus Grampus Risso's Dolphin, Grampus griseus Genus Lagenodelphis Fraser's Dolphin, Lagenodelphis hosei Genus Lagenorhyncus Atlantic White-Sided Dolphin, Lagenorhynchus acutus Dusky Dolphin, Lagenorhynchus obscurus Hourglass Dolphin, Lagenorhynchus cruciger Pacific White-Sided Dolphin, Lagenorhynchus obliquidens Peale's Dolphin, Lagenorhynchus australis White-Beaked Dolphin, Lagenorhynchus albirostris Genus Orcaella Australian Snubfin Dolphin, Orcaella heinsohni Irrawaddy Dolphin, Orcaella brevirostris Genus Peponocephala Melon-headed Whale, Peponocephala electra Genus Orcinus Killer Whale (Orca), Orcinus orca Genus Feresa Pygmy Killer Whale, Feresa attenuata Genus Pseudorca False Killer Whale, Pseudorca crassidens Genus Globicephala Long-finned Pilot Whale, Globicephala melas Short-finned Pilot Whale, Globicephala macrorhynchus - Family Platanistoidea, river dolphins Genus Inia Boto (Amazon River Dolphin), Inia geoffrensis Genus Lipotes Chinese River Dolphin (Baiji), Lipotes vexillifer (considered functionally extinct) Genus Platanista Ganges River Dolphin, Platanista gangetica Indus River Dolphin, Platanista minor Genus Pontoporia La Plata Dolphin (Franciscana), Pontoporia blainvillei" "Six species in the family Delphinidae are commonly called "whales" but are strictly speaking dolphins. They are sometimes called "blackfish". Melon-headed Whale, Peponocephala electra Killer Whale, Orcinus orca Pygmy Killer Whale, Feresa attenuata False Killer Whale, Psudorca crassidens Long-finned Pilot Whale, Globicephala melas Short-finned Pilot Whale, Globicephala macrorhynchus" Source and further information: http://en.wikipedia.org/wiki/Dolphin 3) porpoises: "Porpoises are small cetaceans of the family Phocoenidae; they are related to whales and dolphins. They are distinct from dolphins, although the word "porpoise" has been used to refer to any small dolphin, especially by sailors and fishermen. The most obvious visible difference between the two groups is that porpoises have flattened, spade-shaped teeth distinct from the conical teeth of dolphins." "Kingdom: Animalia Phylum: Chordata Class: Mammalia Order: Cetacea Sub-order Odontoceti Family: Phocoenidae (Gray, 1825) Genera Neophocaena - Finless porpoise Phocoena - Harbour porpoise et al. Phocoenoides - Dall's porpoise" "Family Phocoenidae: Porpoises Genus Neophocaena Finless Porpoise, Neophocaena phocaeniodes Genus Phocoena Harbour Porpoise, Phocoena phocoena Vaquita, Phocoena sinus Spectacled Porpoise, Phocoena dioptrica Burmeister's Porpoise, Phocoena spinipinnis Genus Phocoenoides Dall's Porpoise, Phocoenoides dalli Recently-discovered hybrids between male Harbour porpoises and female Dall's Porpoises indicate that the two species may actually be members of the same genus." Source and further information: http://en.wikipedia.org/wiki/Porpoise