BOSTON 
JOURNAL OF NATURAL HISTORY. 
VOLUME VI. — NO. I. 
Arr. I. —On the Embryology of Nemertes, with an Appen- 
dix on the Embryonic Develop;ent of Polynóe; and 
Remarks upon the Embryology of Marine Worms in 
general. By E. Desor. 
Tuere is no group of animals the true affinities of which 
are more difficult to ascertain, than the so called white-blooded 
Worms. Not only the family, the order, but the class, and 
even in certain cases the department to which they belong is 
doubtful. Some light might therefore be expected from 
the study of their embryological development, according to 
the principle that each type in the animal kingdom follows, in 
this respect, a rule of its own. This consideration, together 
with the interest that attaches itself naturally to all inquiries 
in embryology, induced me to follow out the development of 
the Nemertes. 
The Nemertes are marine worms of a very simple appear- 
ance, having no external gills, and no appendages of any kind.’ 
\Some of them are very long and ribbon-shaped, like Tzenia ; 
' The anatomy of Nemertes has been investigated with great care, by the able 
French naturalist, M. De Quatrefages. (See Cuvier, Regne Animal illustré.) The 
species of the coast of Great Britain have been thoroughly described by Mr. Johns- 
ton in the Magazine of Zoólogy and Botan 
JOURNAL B. S. N. H. l ocT. 1848. 
