254 
and contains numerous protoplasma-poor cells. In the sphincter 
region the mesogloea is considerably thickened. The endodermal 
circular muscles are weak, the sphincter strong, mesogloeal and 
distinctly stratified (textfig. 44) especially in its under part. In one 
of three examined specimens the upper part of the sphincter was 
reticular but with distinet tendency to stratification, the strengest 
Figs. 44—46. Cricophorus nutrix. Transverse section of parts of the sphincter, 
in fig. 46 with curious ectodernial canals (compare the text). 
mesogloea-balks were namely extended in transverse direction (text¬ 
fig. 45, part of the sphincter, spec. from Island Bay). The sphincter 
is wholly separated from the circular muscles of the column. Its 
muscle meshes are usually rather small but numerous, in the reti¬ 
cular part larger. In the sphincter region of the specimen from 
Wellington there were curious transverse ectodermal canals (text¬ 
fig. 46) extended in tangential direction. Their lumen was small also 
at the communication with the ectoderm of the column, their ecto- 
derm at the beginning of the invagination very high, at the end 
considerably thinner. The canals end in the mesogloea and do not 
