1895 B.--Supplementary notes on the systematic position of the trilobites. Quart. Jour. Geol. Soc., London, vol. 51, pp. 352-360, figs. A-C. Beyrich, E. 1846.--Untersuchungen ueber Trilobiten. 2. Stück, p. 30, pl. 4, fig. 1c. Billings, E. 1870.--Notes on some specimens of Lower Silurian trilobites. Quart. Jour. Geol. Soc., London, vol. 26, pp. 479-486, pls. 31-32. Abstract in Geol. Mag., vol. 7, p 291, and Nature, vol. 2, p. 94. Brongniart, A. 1822.--Histoire naturelle des crustacés fossiles. Paris. Brünnich, F. E. 1781.--Beskrivelse over trilobiten, en dyreslaegt og dens arter, med en ney arts aftegning. Nye Samlig of det Kong. Danske Vidensk. Selskabs. Skriften, Copenhagen. Burling, L. D. 1916.--Pædeumias and the Mesonacidæ, with description of a new species, having at least 44 segments, from the Lower Cambrian of British Columbia. Ottawa Nat., vol. 30, pp. 53-58, pl. 1. 1917.--Was the lower Cambrian trilobite supreme? Ibid., vol. 31, pp. 77-79, text figs. 1-2. Burmeister, H. 1843.--Die Organisation der Trilobiten. Berlin. 1846.--The organization of trilobites, deduced from their living affinities. Eng. translation, Ray Society, London. Calman, W. T. 1909.--Crustacea, in "A treatise on zoology," edited by Sir Ray Lankester. London. 1919. Dr. C. D. Walcott's researches on the appendages of trilobites. Geol. Mag., dec. 6, vol. 6, pp. 359-363, pl. 8, text fig. 1. Carpenter, G. H. 1903.--On the relationships between the classes of Arthropoda. Proc. Roy. Irish Acad., vol. 24, pp. 320-360, pl. 6. Castelnau, F. DE. 1843.--Systeme Silurien de l'Amérique Septentrionale, p. 15, pl. 2, figs. 1, 4. Clarke, J. M. 1888.--The structure and development of the visual area in the trilobite, _Phacops rana_ Green. Jour. Morph., vol. 2, pp. 253-270, pl. 1. Crampton, G. C. 1916.--The phylogenetic origin and the nature of the wings of insects, according to the paranotal theory. Jour. New York Entomol. Soc., vol. 24, pp. 1-39, pls. 1, 2. 1919.--The evolution of the arthropods and their relatives, with especial reference to insects. Amer. Nat, vol. 53, pp. 143-179. Dalman, J. W. 1826.--Om Palæaderna eller de så kallade Trilobiterna. Stockholm, Acad. Handl., pp. 113-152, 226-294. 1828.--Ueber die Palæaden, oder die sogennanten Trilobiten. Nuremberg. Dana, J. D. 1871.--On the supposed legs of the trilobite, _Asaphus platycephalus_. Amer. Jour. Sci. (3), vol. 1, pp. 320-321, 386; Ibid. (3), vol. 3, 1872, pp. 221-222. Also printed in Ann. Mag. Nat. Hist, vol. 7, 1871, pp. 366, 451. Dekay, J. E. 1824.--Observations on the structure of trilobites, and description of an apparently new genus. Ann. Lye. Nat. Hist. New York, vol. I, p. 174, 2 pls.; Isis (Encycl. Zeit.), Oken, 1825 and 1832. Dollo, L.