SOME AQUATIC WORMS, ETC. 207 



7. STRftPHURIS (Fig. 1-52), 



The pedal spines and bristles are arranged alter- 

 nately with each other, as in Fig. 152, and together 

 form a single row of clusters on each side of the lower 

 surface of the body. The spines are 

 slightly curved, long and forked, the 

 bristles being three times their length. 



The mouth is triangular. 



The blood is bright red and the vessels 

 large. 



The body is thread-like, transparent, 

 and may be from one to two inches in ^'spiffllkndbri 

 length. The front end is whitish, the '^i?=°fstrip'''- 

 tail end yellowish. It lives in the mud 

 beneath shallow water, and buries itself with about 

 two-thirds of the tail end protruding and constantly 

 vibrating. When disturbed in disappears into its bur- 

 row with astonishing rapidity. Dr. Joseph Leidy, 

 who discovered this peculiar creature, says: "While 

 walking in the outskirts of the city [Philadelphia] I 

 noticed in a shallow ditch numerous reddish patches of 

 from one to six inches square, which, supposing to be 

 a species of Alga, I stooped to procure some, when to 

 my surprise I found them to consist of millions of the 

 tails of Str^phuris dgilis, all in rapid movement. The 

 least disturbance would cause a patch of six inches 

 square so suddenly to disappear that it resembled the 

 movement of a single body. " 



8. 2E0LOS6MA. 



The bristles are of unequal length, and are arranged^ 

 in clusters of four each, the clusters themselves form- 

 ing a single row on each side of the body. There are 



