No. 4. — Studies from the Newport Marine Zoological Laboratory. 

 Communicated hy Alexander Agassiz. 



XVII. 



Preliminary Observations on the Development of Ophiopholis and Echin- 

 arachnius. By J. Walter Fewkes. 



The following paper considers the development of our common Ophi- 

 uran, Ophiopholis aculeata, Gray, and of the Clypeastroid, Echinarachnius 

 parma, Gray. All the observations were made last summer, those on 

 the former at Eastport, Maine, those on the latter at the Newport Labora- 

 tory, Newport, R. I. 



OPHIOPHOLIS ACULEATA, Gray. 



Few observations have been published on the metamorphosis of our 

 common Ophiopholis. The eggs of 0. acxdeata (hellis, Lym.), according 

 to A. Agassiz,* are laid in bunches, and the young develop without pass- 

 ing through a free plutean stage. He gives two figures of the young 

 Ophiopholis made by L. Agassiz in 1848. 



In " Sea-Side Studies " the young Ophiopholis is said to be carried in 

 a pouch, in which the first stages of development occur.f A figure, one 

 of the two mentioned above, is doubtfully identified as a drawing of the 

 young Ophiopholis in the second number of the Embryological Mono- 

 graphs. J Packard § states that in Ophiopholis the development is direct 

 and without metamorphosis. 



* Embryology of the Echinoderms. Mem. Amer. Acad., Vol. IX., pp. 18 and 22. 

 The pluteus referred to Amphiura squamata in the " Embryology of the Echino- 

 derms," and doubtfully to Amphiura in " Embryological Monographs," may be a 

 pluteus of Ophiopholis. Amphiura squamata, Sars, is viviparous, and has no free 

 pluteus. 



t Sea-Side Studies in Natural History. Marine Animals of Massachusetts Bay, 

 p. 137. 



t Mem. Mus. Comp. Zool, Vol. IX. No. 2, PI. III. Fig. 20. 



§ Zoology for Students and General Readers, p. 110. As nothing is said of 

 direct observation, it is probable that this statement is a compilation probably 

 from those already quoted. 



VOL. XII. — NO. 4. 



