56 
all fishes powerfully feel its influence, and the dcvolopcment 
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, bnrying 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, dill'erent 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 arc 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 lias 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 the 
Wiever and the Launce, both of which harbour in sand ; 
through which to be able to move, this organ must he 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 Lumpsucker it requires 
minute inspection to discover the connecting thread ; the se- 
parate particles, which in this fish are of largo size, appearing 
to hang as loosely as shot in a hag. But in some river fishes, 
as the l’erch and Tench, we are informed that they are pre- 
served in a tenacious slime, that, in the form oi a chain or 
ribband binds them to the spot, and perhaps also affords pro- 
tection from the harsher surrounding fluid, as well as food for 
the supply of their first wants. This glutinous matter, more- 
over, iu 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 full action of the light and heat of a summer’s day ; the 
