No. 9. — Studies from the Neioport Marine Zoological Laboratory. 

 Communicated hy Alexander Agassiz. 



XIII.* 

 On the Development of Certain Wot-m Larvae. By J. Walter Fewkes. 



Prionospio tenuis Verr. (?). 



Plates I. and II. 



The youngest larva (PL I. Fig. 1, PI. II. Fig. 7) of this worm has a trans- 

 parent head and a body which is 2-3 mm. long, tapering uniformly from ante- 

 rior to posterior extremity. The head (PI. I. Fig. 1) has four eye-spots, or 



* The present paper, which is the first to appear under the above title, is one 

 of a series from my Newport Laboratory, of which the following have already 

 been publislied : — 



I. The Development of Salpa. By Wm. K. Brooks, pp.58. 34 cuts. March 



1876. Bull. Mus. Comp. Zool., Vol. III. No. 14, p. 291. 

 II. On the Young Stages of some Osseous Fishes. By A. Agassiz. I. De 

 velopment of the Tail. pp. 10. 2 plates. 1877. Proc. Amer. Acad., Vol 

 XIII. p. 117. 



III. Tlie Development of Lepidosteus. Bv A. Agassiz. pp. 11. 5 plates 



1878. Proc. Amer. Acad., Vol. XIV. p. 05. 



IV. On the Young Stages of some Osseous Fishes. By A. Agassiz. II. Devel 



opment of the Flounders, pp. 24. 10 plates. 1878. Proc. Amer. Acad. 

 Vol. XIV. p. 1. 

 V. On some Young Stages in the Development of Ilippa, Porcellana, and Pin- 

 nixa. By Walter Faxox. pp. 16. 5 plates. April, 1879. Bull. Mus. 

 Comp. Zool., Vol. V. No. 11, p. 25L 

 VI. On tlie Development of Pala3monetes vulgaris. By Walter Faxo^j. 

 pp. 27. 4 plates. September, 1879. BuU. Mus. Comp. Zool., Vol. V. No. 

 15, p. 303. 

 VII. Contributions to a Knowledge of the Tubular Jelly-Fishes. By J. Walter 

 Fewkes. pp. 20. 3 plates. March and April, 1880. Bull. Mus. Comp. 

 Zo51., Vol. VL No. 7, p. 127. 

 VIII. On some Points in the Structure of the Embryonic Zoea. By Walter 

 Faxon, pp. 7. 2 double plates. October, 1880. Bull. Mus. Comp. Zool., 

 Vol. VL No. 10, p. 159. 

 LX. Studies of the Jelly-Fishes of Narragansett Bay. By J. Walter Fewkes. 

 pp. 42. 10 plates (.3 double). February, 1881. Bull. Mus. Comp. ZooL, 

 Vol. VIIL No. 8, p. 141. 

 X. On the Development of the Pluteus of Arbacia. By J. Walter Fewkes. 

 pp. 10. 1 double plate. May, 1881. ]\Iem. Pcnbody Acad. Sci., L 6. 

 XI. On the Acalephaj of the East Coast of New England. By J. Walter 

 Fewkes. pp. 19. 1 double plate. April, 1882. Bull. Mus. Comp. Zool., 

 Vol. IX. No. 8, p. 291. 

 XII. On the Young Stages of some Osseous Fislies. III. By A. Agassiz. 

 pp. 32. 20 plates. 1882. Proc. Amer. Acad., Vol. XVII. p. 271. 



Alexander Agassiz. 



VOL. XI. — NO. 9. 



