SENSORY EPITHELIUM OF MICROSTOMA CAUDAT1 \I . 



43 



the water the ciliated pits and the pharynx are opened and closed 

 in such a manner as to greatly alter the contour of the anterior 

 end. These then constitute invaginated regions of the body- 

 surface which test the character of the water passing over the 

 body and into the pharynx. This being the case it is of interest 

 to see the relation of the central nervous system to the epithelia 

 of the pharynx and of the ciliated pits. 



The central nervous system of Microstoma caudatum Ldy. 

 consists of two anterior ganglia connected by a very short, wide, 

 transverse commissure. Extending from each ganglion is a 

 dorsal, lateral nerve and a ventral, lateral nerve. The ventral, 



FIG. i. 



FIG. 2. 



FIG. i. Diagram of central nervous system showing its relation to ciliated pits 

 and pharynx. CP, ciliated pit lying over dorsal, lateral nerve; P, pharynx; N, 

 posterior commissure connecting the two ventral, lateral nerves. 



FIG. 2. Diagram of a transverse section of Microstoma to show the position 

 of the gustatory epithelium and the posterior nerve commissure. N, posterior 

 nerve commissure lying in contact with the gustatory epithelium of pharynx; 

 DN, dorsal, lateral nerve; E, lumen of enteron. 



lateral nerves are connected by a commissure just posterior 

 to the pharynx (text-figures I and 2, TV). In the posterior floor 

 of the pharynx there is a transverse region of its ciliated epithe- 

 lium, which, so far as we can make out, is free from any ducts of 



