154 DivcUers of the Sea and Shore 



patent, therefore, that the periodic plugging of the en- 

 trance serves not merely to keep the drifting sand out 

 when inundation occurs, but at the same time also to 

 keep in the necessary oxygen to breathe. 



When the larva is turned up at the bottom of the 

 burrow, it proves to be a quite abject and helpless in- 

 dividual. Its length is not more than an inch; and as 

 it attempts to escape its efforts may best be described as 

 a fast crawl rather than a run, for its legs seem to be 

 set somewhat closely together under its short thorax, 

 and as it moves over the ground it is obliged to trail 

 along a cumbersome hind body. The hard armor that 

 encases its head extends over the greater part of the 

 fore body, but the abdomen is soft and vulnerable, and 

 its pale waxlike hue is relieved by markings on the 

 upper part of each segment, making a triple row ex- 

 tending along the back. The segments are seven in 

 number. They are well defined, and from the sides of 

 each projects a little clump of short bristles. But the 

 most remarkable of the animal's appendages is to be 

 found on the fifth segment. This part of its anatomy 

 is slightly enlarged, and viewed from the side a pro- 

 nounced hump occurs, accentuating the already crooked 

 curves of the creature's body. At the peak of this 

 Yiump — that is, on the highest point of the back — two 

 stout, sharp hooks, one sixteenth of an inch long, are 

 set with their points turned upward. These are placed 

 one on each side of the middle line that marks its 

 length, and they in turn are encircled at the base with 

 bristling hairs. 



Although it may not strike one immediately that the 

 bristles on the segments are used for climbing up and 



