818 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



Fig. 3. Diagram, showing action of the protective valves, 

 v', v" , and v"', at the posterior end of tiihe of 

 Hyalincecia tubicola. The arrow indicates the 

 inrush of water closing the valves. 



Fig. 4. Diagram of the same portion of tube, demon- 

 strating position of the same valves when the 

 worm emerges, as shown by the arrow. The 

 valves are then open, the membrane bulging 

 in the opposite direction. 



Fig. 5. Tube of Onuphis conchilega, natural size and in 

 its natural position, the large terminal shell. <7, 

 at the anterior end, overhanging. 



Fig. 6. Tube of same worm overturned. The large 

 anterior shell, a, is shown lying on the sea- 

 bottom, and at the posterior end, p, a small 

 portion of membranous tube is visible. 



Fig. 7. Tube of Onuphis conchilega. Semi-diagram- 

 matic sketch, showing the internal, trans- 

 parent, membranous tube, with its protective 

 valves, v, and the sandy side-walls, iv, exposed 

 by treatment with acid. The end of the mem- 

 branous tube is shown on the underlying shell 

 at the other extremity. x 2. 



Fig. 7a. End view of the above internal tube. The long 

 axis of the ellipse indicates the edges of the 

 valves. x 2. 



Fig. 8. Terminal portion of tube of Nothria pyeno- 

 branchiata, split open to show the internal 

 valves, v, v. From a photograph, slightly 

 enlarged. 



Fig. 9. Tube of Nothria v-illemossii, showing external 

 protective spines. Hough sketch from a 

 specimen in the British Museum. Slightly 

 reduced. 



