56 



all fishes powerfully feel its influence, and the developement 

 of the embryo may be unnaturally hastened by it to its des- 

 truction. The Salmon, Peal, and perhaps most of their Con- 

 geners, make considerable trenches in the sand by the aid of 

 the tail, which becomes excoriated in the operation ; and the 

 Lamprey in like manner, sheds its roe in a channel of its own 

 formation, in both cases the place being again filled up by the 

 labour of the parents, the female performing the largest share 

 of the toil. The Launce takes a more effectual method of 

 concealment even than this, burying itself in the sand, through 

 which it is able to move with almost the same facility as a 

 Mole in the earth, and leaving, as it would seem, the pea in 

 its progress. The Conger and Eel also, are known to bury 

 themselves in sand or mud for concealment, the operation 

 being effected by a sort of rotatory motion, the snout serving 

 as a pivot; and in such a situation it is probable that the roe 

 is deposited, the young emerging as they come to life. It is 

 not a little curious that fishes thus accustomed to burrow in 

 the sand or mud, are supplied with a structure for circulating 

 blood in the tail, different from any thing hitherto discovered 

 in other species and constituting that part a sensitive, and in 

 the Eel and Conger at least, a prehensile organ, by which 

 they are able to seize an object, and through it lift the body 

 over formidable obstructions. In the Eel this structure was 

 first discovered by Dr. Marshal Hall, who has given a beau- 

 tiful figure of it in his work on the circulation of the blood 

 in the lower animals, plate 10, from which it has been copied 

 by Mr. Yarrell ; but I have also recognized something extra- 

 ordinary in the circulation of the blood in the tail of Ihe 

 Wiever and the Launce, both of which harbour in sand ; 

 through which to be able to move, this organ must be endued 

 with some sensibilities not common to many other fishes. 



In most sorts of sea fishes the separate particles of roe 

 when deposited have no bond of connection with each other ; 

 and even in the ovarium of the Great Lunipsucker it requires 

 minute inspection to discover the connecting thread ; the se- 

 parate particles, which in this fish are of large size, appearing 

 to hang as loosely as shot in a bag. But in some river fishes, 

 as the Perch and Tench, we are informed that they are pre- 

 served in a tenacious slime, that in the form of a chain or 

 ribband binds them to the spot, and perhaps also affords pro- 

 lection from the harsher surrounding fluid, as well as food for 

 the supply of their first wants. This glutinous matter, more- 

 over, in some cases produces a further effect, in addition to 

 its own nourishing and protecting qualities; and I have seen 

 an abundance of the roe of some inhabitant of the ocean, 

 floating on the surface for several miles in length, exposed to 

 the lull action of the light and heat of a summer's day ; the 



