Family Illaenidae Hawle & Corda, 1847

Remarks. Reed (1915, 1917) figured and described a number of Illaenus species under open nomenclature, mostly from cranidia alone. Illaenids are difficult to characterize even with the benefit of complete specimens, and almost impossible to determine from cranidia without other sclerites. Reed mostly compared his material with species known from the Russian platform, but there are few critical characters, and these specimens are figured here for the sake of completeness. The species in question are Illaenus aff. schmidti, I. cf. esmarki and I. aff. caecoides from the Shihtien Formation, Yunnan, and I. aff. portlocki from Hwe-Mawng, northern Shan State.