Suborder III. PHYSETEROIDEA. Physeteroidea, _Gray_, _l. c._ p. 195; _Synops. Whales & Dolph._ p. 3. Physeteridæ (Physeterinæ), _Flower_, _Tr. Zool. Soc._ vol. vi. p. 113. Head blunt. Nostrils longitudinal, parallel, or diverging, each covered with a valve, the right often obliterated. Teeth many in the lower jaw, fitting into holes in the gums of the upper one. Lachrymal bone none distinct. “Costal cartilages not ossified. The hinder ribs losing their tubercular and retaining their capitular articulation with the vertebræ. The greater number of the cervical vertebræ ankylosed together. Pterygoid bones thick, produced backwards, meeting in the middle line, and not involuted to form the outer wall of the postpalatine air-sinus. Symphysis of mandible of moderate or excessive length. No functional teeth in the upper jaw. Mandibular teeth various, often much reduced in number. Lachrymal bones usually large and distinct. Bones of the skull raised so as to form an elevated prominence or crest behind the anterior nares. Orbit of small or moderate size. Pectoral limbs small. Dorsal fin usually present.”—_Flower._ Family 6. CATODONTIDÆ. Catodontina, _Gray_, _l. c._ pp. 386, 387. Catodontidæ, _Gray_, _Synops. Whales & Dolph._ p. 3. Head compressed, truncated in front, very large. Blowers separate, linear, in front of the upper part of the head. Mouth inferior, linear. Pectoral fin short, broad, truncate. Dorsal hump rounded. Skull elongate. Crown concave, surrounded by a high perpendicular wall formed by the doubled-up maxilla and occipital bones. Upper jaw toothless. Atlas free; rest of cervical vertebræ united by their bodies and spines into a consolidated mass. 1. CATODON. Catodon, _Gray_, _l. c._ pp. 196, 386, 387; Synops. Whales & Dolph. p. 3. Physeter, _Flower_, _Trans. Zool. Soc._ vol. vi. p. 309.