THE COAST OF CALIFORNIA. 137 



in all directions, but more especially centrifugally andcen- 

 tripetally. Their motion is very rapid, and they often twist 

 themselves in a single coil. Their mode of movement is 

 similar to that of other Bryozoa and markedly different 

 from that of the hydroids. Their external surface is 

 richly ciliated. 



Many wheel-like structures were observed through the 

 outer body walls of the capitulum. These bodies bear a 

 close likeness to immature polypides with the undeveloped 

 tentacles retracted giving them a radiated appearance, their 

 tips being folded inward. The wheel-like structures are 

 often pressed together and are most numerous near the 

 lower pole of the capitulum at its point of union with the 

 stalk. The more developed polypides thus lie at the dis- 

 tal pole of the capitulum. 



The stem or stalk has a somewhat exceptional anatomi- 

 cal structure. It is a long, jointed body fastened at one 

 extremity to some foreign body, and supporting the capit- 

 ulum or colonial body of the animal. Its wall has a tough 

 leathery character and is of the same color as the capit- 

 ulum. The stalk is composed of a number of segments, 

 externally indicated by ferrules of uniform size with the 

 indentations well marked. 



The stem is flexible and may be so bent as to bring the 

 capitulum to the level of attachment of the stem, forming 

 a bow. It is sensitive and quickly responds when pinched 

 or otherwise irritated. The motion is slow and graceful. 

 The stem is without appendages or lateral branches ; the 

 joints are of uniform size, with the exception of the basal, 

 which is slightly expanded. The division of the joints is 

 superficial. 



The outer layer of the stem is translucent, pale brown 

 or dark amber colored. A system of muscular blocks which 

 near the capitulum become spherical can be seen through 



