Variation in the New Zealand Material

As there is considerable variation in the specimens used in this study, it merits description before proceeding with a discussion of records of the species by other authors.

The type specimen of D. brevicaudatus is lodged in the Otago Museum and comprises a stuffed mount of the dorsal surface, labelled “Dasybatus brevicaudatus Hutton (= Trygon brevicaudatus). Dunedin, 1875. Mr. Jewett” It agrees with Hutton's (1875) description and the “Maimai” specimen, and is readily recognised as the type by the small oval tubercle on the centre of the back, as described by Hutton. The shape of the disc varies from the “Maimai” specimen in that the tip of the snout is more acute and extended, and the lateral angles of the pectorals are more pointed. The interorbital width is 6.9 in the width of the disc, the same ratio being 6.0 in the “Maimai” specimen. The tail bears eight middorsal tubercles in front of the serrated spine, the first originating just anterior to the hind edge of the pelvics. In addition there is the small oval tubercle on the centre of the back. In the “Maimai” specimen, as mentioned above, there are nine middorsal tubercles on the tail, with an indication of a tenth, while in J. Bollon's specimen there are seven. The Rev. Stock's specimen has only one large tubercle just anterior to the serrated spine, and similarly there is only one on F. M. Begley's specimen, though in the latter case it is evident that only part of the tail is present. Hutton describes two serrated spines on the tail of the type specimen, but of these only a 3-inch fragment of the larger and