Features of the valid nominal species of Aprionodon Gill (isodon Valenciennes) and Hypoprion Müller and Henle (hemiodon Valenciennes, macloti Müller and Henle, and signatus Poey), plus those of a previously unrecognized species here described as Carcharhinus leiodon n.sp., are examined and compared with those of Carcharhinus Blainville. Features studied include morphometrics, vertebral numbers and other vertebral characteristics, tooth numbers, color pattern, and some other aspects of external morphology. It is concluded that on these features C. Leiodon n.sp. is entirely encompassed within the parameters of Carcharhinus, and that, although A. isodon, H. hemiodon, H. macloti, and H. signatus each extend the range of diversity of Carcharhinus in one or more features, A. isodon is not uniquely different from Carcharhinus, and there is no common pattern of difference between the three species of Hypoprion and Carcharhinus. Accordingly, and because the nature of the teeth of Aprionodon and Hypoprion has been found insufficient to warrant generic distinction from Carcharhinus, the genera Aprionodon and Hypoprion are synonymised with Carcharhinus. A diagnosis and description are given for each of the above species. The descriptions include measurements, counts, and line illustrations that show the whole shark in lateral view, underside of head, nostril, and teeth. The geographic distribution is summarized, as are also the meager biological data available on number of embryos, size at birth, size at sexual maturity, and maximum size.

A complete reference to all the sharks inhabiting North American waters, with excellent color illustrations of all the species.

The Darwin Elasmobranch Biodiversity Conservation and Management project in Sabah held a three-day international seminar that included a one-day workshop in order to highlight freshwater and coastal elasmobranch conservation issues in the region and worldwide, to disseminate the result of the project to other Malaysian states and countries, and to raise awareness of the importance of considering aspects of elasmobranch biodiversity in the context of nature conservation, commercial fisheries management, and for subsistence fishing communities. These proceedings contain numerous peer-reviewed papers originally presented at the seminar, which cover a wide range of topics, with particular reference to species from freshwater and estuarine habitats. The workshop served to develop recommendations concerning the future prospects of elasmobranch fisheries, biodiversity, conservation and management. This paper records those conclusions, which highlight the importance of elasmobranchs as top marine predators and keystone species, noting that permanent damage to shark and ray populations are likely to have serious and unexpected negative consequences for commercial and subsistence yields of other important fish stocks.