Walcott figured one individual of this species showing long slender antennules projecting in front of the cephalon. It is of especial interest because one of the antennules shows almost exactly the same sigmoid curvature which is so characteristic of the related _Triarthrus_. The individual segments are not visible. _Measurements:_ The specimen is 23 mm. long and the direct distance from the front of the head to the anterior end of the more perfect antennule is 9.5 mm. Measured along the curvature, the same antennule is about 11 mm. long. _Horizon and locality:_ Same as the preceding. The Appendages of Kootenia. =Kootenia dawsoni= Walcott. Illustrated: Walcott, Smithson. Misc. Coll., vol. 67, 1918, pl. 14, figs. 2, 3. One specimen figured by Doctor Walcott shows the distal ends of some of the exopodites and endopodites of the right side. He compares the exopodites with those of Neolenus, stating that the shaft consists of two segments, the proximal section being long and flat, fringed with long setæ, while the distal segment has short fine setæ. The endopodite best shown is very slender, and the segments are of uniform width and only slightly longer than wide. Measurements (from Walcott's figures): Length of specimen, about 41 mm. Length of five distal segments of an endopodite, 7.5 mm. Since the pleural lobe is only 7 mm. wide, the endopodites, and probably the exopodites also, must have projected a few millimeters beyond the dorsal test when extended straight out laterally. Formation and locality: Burgess shale, Middle Cambrian, on the west slope of the ridge between Mount Field and Wapta Peak, above Field, British Columbia. The Appendages of Calymene and Ceraurus. HISTORICAL. All of the work on these species has been done by Doctor Walcott, who summarized his results in 1881. In the first of his papers (1875, p. 159), Walcott did not describe any appendages but paved the way for further work by a detailed and accurate description of the ventral surface of the dorsal shell of Ceraurus. He demonstrated the presence in this species of strongly buttressed processes which extend directly downward from the test just within the line of the dorsal furrows. One pair of these is seen beneath each pair of the glabellar furrows, each segment of the thorax has a pair, and there are four pairs on the pygidium. He pointed out also that these projections were but poorly developed on that part of the glabella which is covered by the hypostoma. He called them axial processes, the only name which appears to have been suggested thus far.