AUTHOR’S ABSTRACT OF THIS PAPER ISSUED 
BY THE BIBLIOGRAPHIC SERVICE, JUNE 12 
THE NERVOUS SYSTEM OF PHORONIDA 
WILLIAM A. HILTON 
Department of Zoology, Pomona College, Claremont, California 
SIX FIGURES 
It has long been known that the nervous system of Phoronida 
was of the surface or epithelial type, such as we find in Echino- 
dermata, Enteropneusta, and some others. Caldwell (’83) 
was one of the first to describe this condition in Phoronis. He 
mentions nerve processes in connection with the ectoderm. 
According to him, both fibers and ganglion cells occur in the 
surface. Concentrations of nervous tissue occur about the 
mouth, forming a post-oral nerve ring. This ring forms a 
semicircular line along the base of the tentacles. ‘Two ciliated 
pits occur each side of the middle line, and these are considered 
to be sense organs. On the left the nervous system seems to be 
continued as a single thick strand near the surface of the body 
just outside the basement membrane. This rod or strand of 
tissue Caldwell considers to be a hollow cord. McIntosh (’88) 
describes a similar condition in P. buskii; the general form is the 
same; the ciliated pits are also recognized; the epithelial nervous 
system has sense cells and ganglion cells and on the left side is 
the longitudinal nerve cord or tube, shown but not discussed. 
Andrews (’90), in a new species of Phoronis, describes the 
‘glandular pit’ of the lophophore and a ‘‘large nerve cord on the 
left side.”’ He considers it to be solid and surrounded by epider- 
mal cells. According to him, it seems to have a finely fibrillated 
or possibly a ‘coagulated’ structure. This nerve cord, so-called, 
connects directly with the left side of the brain or central nervous 
system and runs the length of the body. On the right a similar 
trunk continues but a short distance. 
Benham (’89) finds the nervous system immediately below the 
epidermis as Caldwell was first to observe. Nerve cells and 
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