234 The Naturalist of Cumbrae. 



would take a man his whole lifetime thoroughly to 

 examine and explain in all the points of its develop- 

 ment, habits, and structure. Also, for any attempt 

 at a full investigation there is scarcely anything 

 more advantageous than that the animal should be 

 common. 



"In the early part of 1868," Mr. Robertson says, 

 "on the shores of Cumbrae, my attention was attracted 

 to many holes occurring in the sand. In tracing them 

 to a depth of four or five inches, I found an Amp hi- 

 dotus cordatus under each hole. The diameter of 

 the hole was about equal to that of a crowquill, and 

 often irregular, and rose straight over the long spines 

 surrounding the dorsal impression of the test. By 

 placing one of the animals in a glass jar with two or 

 three inches of sand below and over it, and covering 

 the whole with water, an opportunity was afforded of 

 seeing how the holes were produced and kept open. 

 Long contractile processes, with tentaculated heads 

 described by Forbes as * long ringed worm-like 

 suckers,' and by Johannes Miiller as 'locomotive 

 feet ' were thrust up through the sand, and were seen 

 slowly, and apparently searchingly, wandering over 

 its surface, then grasping particles of the sandy 

 matter in their tentacles, and finally dragging them 

 rapidly down into the hole. As these holes extend 

 from four to five inches into the sand, and I have 

 seen these prehensile tentacles stretch between two 

 and three inches over its surface, the length of these 

 instruments cannot be less than six or seven inches." 



It is certainly a weird sight to watch, with the aid 

 of a strong lens, one or more of these thread-like 



