||P.2 middle column 2nd paragraph: "Extinction rates from cohort analyses average about 100 E/MSY (Table 1). Local rates from regions can be much higher: 305 E/MSY for fish in North American rivers and lakes (ref 34), 954 E/MSY for the region’s freshwater gastropods (ref 35), and likely >1000 E/MSY for cichlid fishes in Africa’s Lake Victoria (ref 36)." P.2 middle column 4th paragraph: "How does incomplete taxonomic knowledge affect these estimates? Given that many species are still undescribed and many species with small ranges are recent discoveries, these numbers are surely underestimates. Many species will have gone or be going extinct before description (refs 8, 15). Extinction rates of species described after 1900 are considerably higher than those described before, reflecting their greater rarity (Table 1). Moreover, a greater fraction of recently described species are critically endangered (Table 1). Rates of extinction and proportions of threatened species thus increase with improved knowledge. This warns us that estimates of recent extinction rates based on poorly known taxa (such as insects) may be substantial underestimates because many rare species are undescribed."