Eclieneis lunula. 415 



repose these lamince are inclined obliquely backwards, the posterior 

 emerging from behind the anterior, and they lie in such close contact 

 that there can scarcely be any void between them : but when the fish, 

 after having attached itself by its disk requires to take the firmest hold 

 of an object, it draws the lamince, by means of the muscular apparatus of 

 the organ, into a direction nearly perpendicular to the surface of attach- 

 ment, and retains them in that position by the triple series of teeth on 

 the edge of each lamina, the spaces naturally existing between the 

 lamince to the depth of about the fifth of an inch being at the same 

 instant extended to their greatest capacity, and each contributing to 

 form a considerable vacuum. So long therefore as this combined action 

 is kept up, the disk remains immoveable. 



That the spare disk in the cask may be as little incomplete as possi- 

 ble, I inclose for Mr. Bennett three of the bones I had removed from it, 

 one answering to the spinous process of a xiertebra and the others form- 

 ing two of the above moveable lamince. 



Before I conclude with this genus, I may notice a couple of errors that 

 authours have fallen into concerning their motions. M. Risso, for example, 

 describes them as lazy and slow ; yet all admit that they contrive to fix 

 themselves to fishes of great velocity, and in these seas they are very 

 often found upon Sharks : how could they reach these, how could they 

 detach themselves from their '* conducteurs" to catch their fiseces (on 

 which Bosc asserts that they feed), and come up with them again, unless 

 they were enabled to move with great speed ? Some of our oldest fish- 

 ermen here tell me that, although the Eclieneis swims at a moderate rate 

 when lounging, or going round their canoes in search of food, it will 

 pursue its prey with great quickness; and to me the lengthened-conical 

 form of its body, and the length and size of its dorsal, anal, and caudal 

 fins, appear to be well adapted for great speed. 



Another error, as I deem it, is that the Ec/ieneidce swim resupinately ; 

 yet prima facie, this seems improbable, and no fisherman here has ever 

 observed them swimming in that position. 



There is a small J^furse in the cask, of which I sent you a specimen 

 last year. I have since then detected the spiracles; they were very 



