EULIMA ON AND IN HOLOTHUEIA. 



351 



has only led to its losing the organ for gnawing and masticating 

 which is universal and peculiar to univalves. It does not need 

 it, for it seems to suck up the slimy secretion from the skin of 

 the host. Hence Eulima has never been included in the 

 category of true parasites ; and rashly dogmatising from this 

 view, the actual observation of Mr. Cuming (the well-known 

 traveller and conchologist), who found similar specimens of 

 Eulima inside the stomach of Holothurians, was at once rejected 

 and explained away by the quite unfounded assertion that the 

 univalves had only been eaten by the Holothurians; but 

 Cuming was perfectly correct in his statement, for I myself 

 have found living Eulimse in the intestine of large Holothurise, 



Fli3. 95. — Two uudescribed species of Evllrm. a, lives creeping freely in the stomach of 

 a Holothurian. 6 is sessile on the skin of a Holotliurian, through which it plunges 

 its sucking proboscis, c, the front of the proboscis with its simple mouth. 



and that very often and by no means as a great rarity. Here 

 they creep about rapidly on their broad foot, on the wall of 

 the intestine, and they have, moreover, all the organs proper to 

 univalves, as a nervous system, organs of sensation, an intes- 

 tinal canal, &c., exactly like the form living on the outer skin ; 

 the only organ wanting is, ia the same way, the masticating 

 organ, rachis or tongue, as it is called. With these, certain small 

 flat worms live in the same intestine ; these have the internal 

 structure of the Trematoda, but glide along the intestinal 

 canal after the fashion of the Planarian worms, by means of 

 the cilia on their skin; and, lastly, a few species of minute 

 Crustacea, belonging to the Copepoda, float and crawl within 



