80 ANIMAL PARASITES AND MESSMATES, 



die in the course of evolution, are under the care of 

 an especial attendant, employed to make away from 

 time to time with the addled eggs, or the embryos that 

 have failed to come to maturity. 



In this manner lobsters give lodgings in the midst of 

 their eggs to a worm, which we at first took for a Ser- 

 pula, and which, after a complete examination, turns out 

 to be one of the Hirudinidae : we have given it the name 

 of Histriohdella. It is as singular in its movements as 

 in its conformation, and its manner of living approaches 

 that of the Pontohdellse of the rays, of which we shall 

 speak subsequently. We announced this discovery a few 

 years ago in the following terms : — 



It is known that lobsters, as well as crabs and the 

 greater part of the Crustacea, carry their eggs under the 

 abdomen, and that these eggs remain suspended there 

 till the embryos are hatched. In the midst of them lives 

 an animal of extreme agility, which is perhaps the most 

 extraordinary being which has been subjected to the eyes 

 of a zoologist. It may be said, without exaggeration, 

 that it is a biped, or even quadruped, worm. Let us 

 imagine a clown from the circus, with his limbs as far 

 dislocated as possible, we might even say entirely de- 

 prived of bones, displaying tricks of strength and activity 

 on a heap of monster cannon balls, which he struggles 

 to surmount ; placing one foot formed like an air- 

 bladder on one ball, the other foot on another, alter- 

 nately balancing and extending his body, folding his 

 limbs on each other, or bending his body upwards like 

 a caterpillar of the geometridae, and we shall then have 

 but an imperfect idea of all the attitudes which it 

 assumes, and which it varies incessantly. 



