1896.] Embryology. 687 
sections. The outer tentacle sheath retains the same circumference in 
about thirteen sections. As soon as the canal and glandular tissue 
have disappeared the circumference of the outer sheath lessens in both 
the six posterior sections and the six sections anterior to the thirteen 
Ẹ Zoo My» 
Figure III. T, tentacle; mx,* branch of ramus maxillarios; other letters same 
as in figure IT. 
median sections until it is only one fourth of the full size and the cells 
of the sheath become scattered, thus finally filling up the central area 
and creating a solid cord in the last two sections. It is worthy of 
notice that this tentacular apparatus was observed on the right hand 
side only in the specimen examined. In three other specimens of the 
same hatching, though they were several millimeters longer, no trace of 
the above described organ could be discerned. Kingsley has shown 
that no such organ exists in his specimens which were from the same 
lot as mine. An explanation of the occurrence of this organ in only 
one specimen may be found in the fact that it is an exceedingly transi- 
tory formation like the pronephros of the chick, which is present for 
only one day. ; 
The second objection Kingsley makes to my observations, is that all 
the eye muscles are present in Amphiuma and the Sarasins say the re- 
tractor muscle of the tentacle is probably developed from the retractor 
bulbi. To this I answer that the Sarasins have not been able to demon- 
strate positively that the retractor muscle is developed from the retrac- 
tor bulbi, and if it were true that the retractor muscle is developed 
from the retractor bulbi, I see no objection to the posterior part of the 
