Letters

American Zoo; Aquarium Association; Old Georgetown Road; Bethesda; Md U.S.A.; Department of Animal& Plant Sciences; University of Sheffield; Sheffield S10 Tn; United Kingdom; Institute of Zoology; Zoological Society of London; Regent's Park; London Nw1 Ry; United Kingdom; Durrell Institute of Conservation& Ecology; Department of Biosciences; University of Kent; Canterbury; Kent Ct2 Nj; United Kingdom; Bio-Resources Inc.; East Center; Logan; Ut U.S.A.; National Museum of Natural History; Msc Mrc Institution; Washington; D.C. address:; University of Alaska Museum; Yukon Drive; Fairbanks; Ak ffksw@ aurora.alaska.edu>