ARCHIVES 



ZOOLOGIE EXPÉRIMENTALE ET (lÉNÉIlALE 



KONDKES PAR 



H. DE LACAZE-DUTHIERS 



PUBLIÉES SOUS LA DIRECTION DE 



G. PRUVOT ET E. G. RACOVITZA 



Chargé de Cours à la Sorboiine Docteur es sciences 



Directeur du Laboratoire Arago Sous-Directeur du Laboratoire Arago 



A'^ SÉRIE, T. II. NOTES ET REVUE 1004. N- -2 



IV 



THE DEVELOPMENT OF PHASCOLOSOMA 

 (Preliminary Note) 



by John H. Gehould Ph. D. 

 Dartmoutb Collège, Hanover, N. H. United-States. 



Thanks to the generous hospitality of the laie dircclor and 

 founder of the Laboratoire Lacaze-Duthiers, I hâve been enabled 

 to extend the studies upon the embryology of Phascolosoina which 

 I began in America at the private laboratory of Dr. Alexander 

 Agassiz at Newport R. L This work, which is nearly completed, 

 consists in the study of the entire course of development of Pluis- 

 colosoma vulgare Blainville, of the English Channel and, witi» the 

 exception of the later stages of cleavage, oïPh. Gouldii Diesing, of 

 the coast of the United States. I hâve studied also the eggs and 

 larval development of Ph. elongatum Keferstein, the siiialh-r 

 species, of a darker brown color, which is found in sucii abuiulanoe 

 with Ph. vulgare at Pempoul, near Roscoff. 



ARCH. DE ZOOL. EXP. ET GÉN. — 4« SÉRIE. — T. 11. 1904 " 



