256 O. E. Beecher — Morphology of Triarthrus. 



References. 



I. Beecher, C. E., 1893. — A Larval Form of Triarthrus. This Journal, III, 



vol. xlvi, pp. 361, 3G2, November. 



2. 1893. — On the Thoracic Legs of Triarthrus. This Journal, 



III, vol. xlvi, pp. 46*7-470, December. Abstract of a paper 

 " On the Structure and Development of Trilobites," read 

 before the National Academy of Sciences, November 8th. 



3. 1894. — On the mode of occurrence, and the structure and 



development of Triarthrus Becki. American Geologist, vol. 

 xiii, pp. 38-43, PI. Ill, January. Abstract of a paper " On 

 the Structure and Development of Trilobites," read before 

 the National Academy of Sciences, November 8th, 1893. 



4. 1894. — The Appendages of the Pygidium of Triarthrus. This 



Journal, III, vol. xlvii, pp. 298-300, PI. VII, April. Read 

 before the Conn. Acad. Arts and Sci., March 21st. 



5. 1895. — Further observations on the ventral structure of Tri- 

 arthrus. American Geologist, vol. xv, pp. 91-100, Pis. IY, 

 V, February. 



6. 1895. — The Larval Stages of Trilobites. American Geologist, 



vol. xvi, pp. 166-197, Pis. VIII-X, September. 



7. Bernard, H. M., 1894.— The Systematic Position of the Trilobites. Quar. 



Jour. Geol. Soc. London, vol. 1, pp 411-432, August. Read 

 March 7 th. 



8. ! 1895. — Supplementary notes on the Systematic Position of 



the Trilobites. Quar. Jour. Geol. Soc. London, vol. li, pp. 



352-359, August. Read April 24th. 

 9. 1895. The Zoological Position of the Trilobites. Science 



Progress, vol. iv, pp. 33-49, September. 

 10. Matthew, W. D., 1893. — On Antenna? and other Appendages of Triarthrus 



Beckii. This Journal, vol. xlvi, pp. 121-125, PI. I, August. 



Read before N. Y. Acad. Sci., May, and published in Trans. 



N. Y. Acad. Sci., vol. xii, pp. 237-241, PL VIII, July 22d. 



II. Walcott, C. D., 1879.— Fossils of the Utica Slate. Trans. Albany Institute, 



vol. x, pp. 18-38, Pis. I, II, 1883. Author's extras printed 

 « in advance, June, 1879. 



12. 1894. Note on some Appendages of the Trilobites. Proc. 



Biol. Soc. Washington, vol. ix, pp 89-97, PI. I, March 30th. 

 Read March 24th. Geological Magazine, N. S. dec, iv, vol. 

 i, pp. 246-251, PI. VIII, June. 



Explanation of Plate. 



Figure 1 . — Triarthrus Becki Green ; dorsal view ; showing character and 

 extent of antennules and limbs beyond the carapace, x 2-£. 



Figure 2. — Triarthrus Becki Green; ventral view; showing entire series of 

 appendages, together with hypostoma, metastoma, and anal opening. 

 x2i. 



Utica Slate, Ordovician, near Rome, New York. 



