Communicated by the Editorinl Secretary
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INTRODUCTIONOn the 21 May 1959 a specimen of Mesoplodon mirus True stranded a t the Wilderness, Cape Province, 170 miles eastward along the South African coast from Cape Agulhas, the southernmost point of Africa. The specimen was saved for the South African Museum by Mr B. L. Cairncross, a local naturalist, and is the first record of the species from the southern hemisphere. The stranding has been briefly recorded by one of us (Talbot, 1960). This paper attempts a fuller description of the specimen, and provides a key to the species of the genus Mesoplodon in South Africa. QENUS Mesoplodon QERVAIS Moderately sized whales attaining a length of under 6000 mm. (20 ft.) in both sexes.Head moderate in size, with a shallow nuchal depression ; rostrum prominent (usually longer in females) ; lower jaw slightly exceeding the upper; 2 teeth, 1 in each ramus a t the extremity ofthe mandibular symphysis (in M . mirus), or near or a t the posterior union of the symphysis (all other species); erupted in males only, unerupted (and functionless) in females. Teeth variable according to species, strongly compressed laterally ; no teeth in maxillae (vestigeal teeth occasionally present in upper or lower jaw or both). A pair of diverging gular grooves forming an inverted V-shape, the arms not in contact anteriorly; the grooves following the angle of the rami, no thoracic or abdominal pleats. Blowhole median, crescentic, concave anteriorly. Eyes moderate in size. Body fusiform, compressed, particularly posteriorly, deepest about the middle. Flippers moderate in size, sub-acute ; flukes moderately large, without median notch; dorsal fin nearer the caudal, well behind the centre of the body, triangular or somewhat falcate. Genital slit is separated by an interval from the anus in male ; genital and anal openings within the same slit in the female.Vertebral formula : C . 7 (first three normally fused, sometimes also the fourth and very occasionally a part of the fifth, sixth and seventh free) ; D . 9 to 10; L. 10 or 11 ; Cd. 19 or 20. Sternum of 4 or 5 elements.
