4-O THE APPENDAGES, ANATOMY, AND RELATIONS OF TRILOBITES. 



figs. 12-14; pl- IO > fig- !> Amer. Jour. Sci., vol. i, 1896, pj. 8; Geol. Mag., dec. 4, vol. 3, 1896, pi. 9; 

 Eastman-Zittel Text-book of Paleontology, vol. I, 1900, text figs. 1267-1269; 2d ed., 1913, fig. 1375; Studies 

 in Evolution, 1901, reprint of all previous figs.; Amer. Jour. Sci., vol. 13, 1902, pi. 2, figs. 1-5; pi. 3, fig. i; 

 pi. 4, fig. i; pi. 5, figs. 2-4; Geol. Mag., dec. 10, vol. 9, 1902, pis. 9-11, text figs. 1-3. Walcott, Proc. 

 Biol. Soc. Washington, vol. 9, 1894, P'- *> fis s - J "6; Geol. Mag., dec. 4, vol. i, 1894, pi. 8; Smithson. Misc. 

 Coll., vol. 67, 1918, pi. 29, figs. l-ii; pi. 30, figs. 17-20; pi. 32; pi. 34, figs. 4-7; pi. 35, fig. 5. Bernard, Quart. 

 Jour. Geol. Soc., London, vol. 50, 1894, text figs, n, 12. CEhlert, Bull. Soc. Geol. France, ser. 3, vol. 24, 1896, 

 text figs. 1-17, 34. Jaekel, Zeits. d. d. geol. Gesell., vol. 53, 1901, text fig. 24. Moberg, Geol. Foren. Forhandl., 

 vol. 29, pt. 5, 1907, pi. 4, fig. 2; pi. 5, fig. i. Handlirsch, Foss. Insekten, 1908, text fig. 6. Tothill, Amer. 

 Jour. Sci., vol. 42, 1916, p. 380, text fig. 5. Crampton, Jour. N. Y. Entomol. Soc., vol. 24, 1917, pi. 2, fig. 20. 



HISTORICAL. 



Specimens of Triarthrus retaining appendages were first obtained by Mr. W. S. Valiant 

 from the dark carbonaceous Utica shale near Rome, New York, in 1884, but no consid- 

 erable amount of material was found until 1892. The first specimens were sent to 

 Columbia University, and were described by Doctor W. D. Matthew (1893). This article 

 was accompanied by a plate of sketches, showing for the first time the presence of antennules 

 in trilobites and indicating something of the endopodites and exopodites of the appendages of 

 the cephalon, thorax, and pygidium. Specimens had not yet been cleaned from the lower 

 side, so that no great amount could then be learned of the detailed structure. Matthew con- 

 cluded that "The homology with Limulus seems not to be as close in Triarthrus as in the 

 forms studied by Mr. Walcott; but the characters seem to be of a more comprehensive type, 

 approaching the general structure of the other Crustacea rather than any special form." 



Professor Beecher's first paper, dated October 9, 1893, merely mentioned the fact that 

 the Yale University Museum had obtained material from Valiant's locality, but was quickly 

 followed by a paper read before the National Academy of Sciences on November 8, and 

 published in December, 1893. This paper described particularly the thoracic appendages. 



This was followed in January (1894 A) by an article in which some information about 

 the mode of occurrence of the specimens was added, and in April (1894 B), the limbs of 

 the pygidium were described and figured. The determination of the structure of the appen- 

 dages of the head evidently presented some difficulty, for the article describing this portion 

 of the animal did not appear until the next February (1895 A). This cleared up the ven- 

 tral anatomy of Triarthrus, and was followed by a short article (1896 A) accompanied by 

 a restoration of the trilobite showing all the appendages. 



This ended Professor Beecher's publications on Triarthrus until his final paper in 1902, 

 although he contributed some of his results and figures to his chapter on the trilobites in 

 the Eastman-Zittel Text-book of Paleontology in 1900. 



The discovery of these excellent specimens had of course excited very great interest. 

 Doctor Walcott also studied a number of specimens from Valiant's locality, and published 

 in 1894, with some original figures, the results of his comparison of the appendages of 

 Triarthrus with those of Calymene and Ceraurus, 



In his article on the "Systematic Position of the Trilobites," Bernard (1894) used 

 the results of Professor Beecher's studies of 1893, and also quoted the papers by Matthew 

 (1893) and Walcott (1894), though the article by the latter appeared too late to be used 

 except for a note added while Bernard's paper was in press. A final footnote quoted from 

 Professor Beecher's paper of April, 1894 (1894 B). 



CEhlert (1896) gave an excellent summary in French of the work of Beecher and Wal- 

 cott on Triarthrus, with reproductions of many of their figures. 



