As mentioned in my paper on early trilobite types ( 1940 p. 121 ), Kjerulf ( 1865) introduced a new trilobite species which has not been adopted by later writers on account of incomplete description and apparant lack of type specimen. In his "Veiviser ved geologiske excursioner i Christiania omegn" he gives a scematic woodcut of a complete trilobite specimen which he refers to the new species Illænus glaber, or Illænus Dalm. glaber Musæum Christianiæ. The figure and name is not accompanied by any description, but a certain affinity to a British species is indicated by the reference: "An I. perovalis Murch. Silur. Syst. 661 pl. 23. 7" . The specimen is found at Ladegaardsøen ( = Bygdøy near Oslo) in "etage 4" which comprises chiefly the Middle and Upper Ordovician.