MORPHOLOGY OF TRIARTHRUS 219 



of locomotion, the limbs of the cephalon and pygidium were 

 of feeble assistance compared with those on the thorax, and 

 in the higher Crustacea these two regions are the ones where 

 the greatest branchial specialization takes place. 



References. 



1. Beecher, C. E., 1893. A Larval Form of Triarthrus. Amer. Jour. 



Sci. (3), vol. xlvi, pp. 361, 362, November. 



2. 1893. On the Thoracic Legs of Triarthrus. Amer. Jour. Sci. 



(3), vol. xlvi, pp. 467-470, December. Abstract of a paper " On 

 the Structure and Development of Trilobites," read before the 

 National Academy of Sciences, November 8. 



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



development of Triarthrus Becki. American Geologist, vol. xiii, 

 pp. 38-43, pi. iii, January. Abstract of a paper " On the Struc- 

 ture and Development of Trilobites," read before the National 

 Academy of Sciences, November 8, 1893. 



4. 1894. The Appendages of the Pygidium of Triarthrus. Amer. 



Jour. Sci. (3), vol. xlvii, pp. 298-300, pi. vii, April. Read before 

 the Connecticut Academy of Arts and Sciences, March 21. 



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



t 



arthrus. American Geologist, vol. xv, pp. 91-100, pis. iv, 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. 



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



Trilobites. Quar. Jour. Geol. Soc. London, vol. li, pp. 352-359, 

 August. Read April 24. 



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



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



10. Matthew, W. D., 1893. On Antennae and other Appendages of 



Triarthrus Beckii. Amer. Jour. Sci. (3), vol. xlvi, pp. 121-125, 

 pi. i, August. Read before the New York Academy of Sciences, 

 May, and published in Trans. N. Y. Acad. Sci., vol. xii, pp. 237- 

 241, pi. viii, July 22. 



11. Walcott, C. D., 1879. Fossils of the Utica Slate. Trans. Albany 



Inst., vol. x, pp. 18-38, pis. i, ii, 1883. Author's extras printed in 

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



Biol. Soc. Washington, vol. ix, pp. 89-97, pi. i, March 30. Read 

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 246-251, pi. viii, June. 



