No. 9. — Studies from the Ncioport Marine Zoological Lahoratory. 

 Communicated hy Alexander Agassiz. 



XIII.* 

 On the Development of Certain Worm Larvoe. By J. Walter Fewkes. 



Prionospio tenuis Vekk. (?). 



Plates I. and II. 



The youngest larva (PI. 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 (PL 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 wbich the following have already 

 been published : — 



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



1876. Bull. Mus. Comp. Zoul., Vol. III. No. li, 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. 



xm. p. 117. 



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



1878. Proc. Amer. Acad., Vol. XIV. p. G5. 



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



opment of the Flounders, pp. 1\. 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 Faxon, pp. IG. 5 plates. April, 1879. Bull. Mus. 

 Comp. Zool, Vol. V. No. 11, p. 251. 

 VI. On the Development of Palffimonetes vulgaris. By Walter Faxon. 

 pp. 27. 4 plates. September, 1879. Bull. IMus. Comp. ZoiJL, Vol. V. No. 

 15, p. 303. 

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

 Fewkes. pp. 20. 3 plates. ]\Iarch and April, 1880. Bull. Mus. Comp. 

 Zool., Vol. VI. No. 7, p. 127. 

 VIII. On some Points in the Structure of the Embryonic Zoi-a. By Walter 

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

 Vol. VI. No. 10, p. 159. 

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

 pp. 42. 10 plates (3 double). February, 1881. JBull. Mus. Comp. Zoiil., 

 Vol. VIII. No. 8, p. 141. 

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

 pp. 10. 1 double plate. May, 1881. Mem. Pcabody Acad. Sci., I. 0. 

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

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

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

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

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



Alexander Agassiz. 



VOL. XI. — NO. 9. 



