On Parasitic Animals. 103 



the body of the animals which they inhabit. Here we have 

 the body of a polypus, which has for its parasite a worm, so 

 like the arm of a polypus, that the illusion cannot be greater. 

 Of the two polypi which he produced before the Academy, there 

 was one in which the hexacotyles was attached to one of the arms, 

 which it had even nearly destroyed, and which it seems in such 

 a degree to replace, that at first sight it might be taken for the 

 arm itself. " Let it be judged," said M. Cuvier, " how many 

 theories might be founded on such an extraordinary resem- 

 blance. Never has the imagination been exercised on so curious 

 a subject. As to myself, who have long adhered to the exposition 

 of positive facts, I shall at present confine myself to making 

 known, as accurately as possible, the exterior and interior of our 

 animals." 



Natural History owes the discovery of this worm to the at- 

 tention of M. Laurillard, keeper of the Anatomical Galleries of 

 the Museum of Natural History, who having been sent to Nice 

 to collect the fishes of the Mediterranean, at the same time en- 

 gaged in examining and collecting all the other productions of 

 that sea, so rich and as yet so little knoAvn. 



He found this worm on the Octopus granulatus of M. La- 

 marck. Neither the Octopus vulgaris, nor the Eledone, nor any 

 other cephalopodous animal, was observed by him to furnish 

 any, although he carefully examined them for that purpose ; so 

 that the Hecatocotyles would seem to be peculiar to the Octopus 

 granulatus. 



Of five individuals which fell into the hands of M. Laurillard, 

 there were three in the cavity of a single octopus, with the 

 head attached to some part of its interior, and the tail stretching 

 into the abdominal sac, but without penetrating into the perito- 

 neum. A fourth was found in another octopus, but in a similar 

 position. The fifth alone was attached, as we have said, 

 to an arm of the octopus, and had transformed itself into a 

 kind of bag into which it had introduced its head, the rest 

 of its body remaining free at the exterior. The hecatocotyles 

 is, therefore, properly speaking, but a semi-intestinal, or ra- 

 ther a scnii-cxtcrnal parasite, like the polystomae and trysto- 

 ma*, and like the Icrnea; and chaiidracanthi. It is easily detached 

 from the animal on which it lives, and inmicdiately swims about 



