MARINE BIOLOGICAL STATION AT POET ERIN. 97 



stick them together to form the branched sandy filaments 

 which surround the upper end of the tube. The right- 

 hand lower figure shows the completed structure. Two 

 curious pelagic or free-swimming worms are shown in 



Fig. X., Terebella (about natural size). 

 fig. XII., viz., Sagitta bipunctata at 2, and Tomopteris 

 onisciformis at 4. These are caught on the surface of the 

 sea by means of tow-nets. 



POLYZOA. 



(Fig. XL) 

 On sea-weeds and under stones on the shore there 

 are found many beautiful little colonies of worm-like 

 animals, which, from their compound condition, are called 



