AULACOPLEURINE TRILOBITES FROM THE LLANDOVERY OF NORTHWESTERN CANADA

Aulacopleurine trilobites from Llandovery strata of the Whittaker Form ation in the central Mackenzie Mountains, Northwest Territories, Canad a, include Aulacopleura andersoni n. sp., Aulacopleura? ranfordi n. sp ., and Songkania smithi n. sp. The subfamily Aulacopleurinae consists of only the genera Aulacopleura Hawle and Corda, 1847, and Songkania C hang, 1974, characterized by smooth, broad early growth stages and hol aspides having expanded frontal and genal areas, covered with dense ca ecal pits, but usually very subdued tuberculate sculpture. The relatio nship of Aulacopleura? ranfordi and A.? reedi Pribyl, 1947, to the rem ainder of species assigned to the genus is ambiguous.