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Further Contribution to the Morphology of the Vertebrate Head. 
By Juzıa B. Pratt. 
(Anatom. Laboratory, Freiburg i/Br.) 
With 15 Figures. 
These studies are practically a continuation of work presented 
last October for publication in the Journal of Morphology‘). Through 
the kindness of Prof. WIEDERSHEIM, I have been enabled to continue 
my investigations in his laboratory, and the result of further study 
on the early development of Acanthias is here summarily sub- 
mitted. I gratefully acknowledge my indebtedness to Prof. WIEDERS- 
HEIM for the privileges he has accorded me. I would also acknowledge 
the kind assistance of Dr. KEIBEL. 
1. The Alimentary Canal. 
At the time when the head of Acanthias begins to be folded off 
from the surrounding blastoderm, and while the neural plate is still 
quite flat, the alimentary canal is found to extend to the anterior 
limit of the embryo, lying here in close contact with the ectoderm. 
Cross sections show the canal to extend even further forward than the 
neural plate. Figs. 1 and 2 are sections from the same embryo. 
In fig. 1 the lumen of the alimentary canal first comes into section. 
Fig. 2 is five sections posterior to fig. 1, and passes through the 
AS MATT 
6 \ 
Se BE ae 
Figs. 1 and 2. Sections through an embryo just beginning to be folded off from the 
blastoderm. Fig. 1 is five sections anterior to fig. 2. adi wall of alimentary canal. 
ect ectoderm. 2. ali lumen of alimentary canal. x. pl. neural plate. 
1) J. B. Puart, Contribution to the Morphology of the Vertebrate 
Head, founded on the Study of Acanthias vulgaris. 
