Forty-one species assigned to thirty-seven named genera of trilobites are described from the Tangtou Formation at Tangshan and Lunshan, in Jiangsu Province, SE China. Nankinolithus nankinensis Lu, the Zone fossil of the upper part of the Formation, is abundant. Many Tangtou Formation species occur also in the Huangnehkan, Linhsiang and Chiencaokou formations, and all are considered to be of early Ashgill age. The trilobites are closely related to those of the Staurocephalus clavifrons Zone (Rawtheyan) of Poland, demonstrating the long duration and wide extent of deeper water faunas. There are also close links with the Ashgill faunas of Central Asia.
One new species, Amphitryon cheni, is established. The following morphological features are described: a small remopleuridine hypostome is unlike any other in construction; Nileus transversus retains genal spines to full grown size in some specimens, but loses them in others; the hypostome lacks the posteromedian cusp of other species. The hypostome of Paraphillipsinella is strongly styginid in conformation, and unlike that of Phillipsinella. Telephina convexa is the only species known with three spines on the librigena. The arrangement of pits in Nankinolithus nankinensis, the type species, is described, including illustrations of the irregularities which occur in every fringe. A small bulb at the tip of the hypostome of Ovalocephalus (= Hammatocnemis) bears two backwardly pointing spinules, one above the other, on the vertical posterior margin. Three types of protaspides, and numerous meraspid parts are described.