10 Messrs. Hancock and Embleton on a Gymnetrus 
larger, more projecting, and then occupying the whole inner sur- 
face of the tube. These plicee, which become tortuous and col- 
lected into rows of two or three together, are found to extend to 
the ends of the ovarian cavities, and are studded throughout with 
minute ova of unequal sizes in an undeveloped state. 
The ureter, figs. 2 & 3m, a simple tube of the size of an ordi- 
nary goosequill, runs from the external orifice, just within which 
is a slight vesical dilatation, fig. 3, along the median line, lying 
above and attached to the ovaria, and in contact with the roof of 
the abdominal cavity, for a distance of 1 ft. 1] im., when it per- 
forates the fibrous membrane separating the kidney from the 
other viscera. It runs obliquely forwards and upwards into the 
kidney, fig. 30, which, inclosed in its proper cavity, extends 
from an inch behind where the ureter joins it as far as the cra- 
nium, a distance of 2 ft., reaching farther forward than the di- 
gestive cavity. The organ is partially and unequally cleft by a 
median fissure, the left side being larger than the right, Its 
tissue is reddish brown, spongy and friable. The posterior end 
of the kidney tapers to a point. The anterior end also tapers a 
little, but is rounded. The ureter enters the under surface of 
the gland and terminates by openmg into the general cavity 
which exists along the median line of the organ. Along the 
upper angle of this cavity and elsewhere are the openings of 
small canals bringing the secretion from the uriniferous tubules. 
These last can be readily seen with a common magnifying glass. 
The supra-renal glands, fig. 3p, are two small ovoid bodies, 
much paler than the kidney, partially imbedded in that organ on 
its upper surface at a distance of 2 inches from its posterior ex- 
tremity. There is no trace of air-bladder. 
The heart, which is double the size of that of an ordinary cod- 
fish, occupies a spacious triangular cavity. Its ventricle is large, 
firm and triangular. The bulb of the aorta is smaller than 
that of the cod. The auricle is capacious and of irregular form. 
The blood-vessels beyond were not examined, and we could not 
investigate the nervous system. 
In a little blood obtaimed from the heart, the blood-dises, 
Pl. I. fig. 5, are found to vary much in size, and also in form 
from subcircular to elliptical and even fusiform, having their ex- 
tremities or poles somewhat pointed. The nucleus is generally 
large and distinct, and presents several nucleoli of different sizes, 
giving it in many instances a granular appearance. 
General remarks.—Having referred to what we have been able 
to find recorded respecting the genus Gymnetrus, we found that 
the figures as well as the descriptions of the external parts were 
very imperfect and the anatomy little known ; hence we thought 
it desirable to make the above description fuller than otherwise 
