268 PLEUROBRANCHID/. 
their interstices a red-brown colour meanders in various 
breadths and irregular blotches, interspersed with cloudings 
of pale yellow flakes. The body within, and the internal 
area of the disks, are pale bluish-white, the ventral margins 
being aspersed to an inch in depth with yellowish-white spots, 
but the dorsal ones are plam. The head is a thick muzzle 
springing from the centre of a slightly auricled membrane, 
pale blue on the under surface, and on the upper sprinkled 
with flake-white and red points; under this membrane is the 
mouth, within which is a spmous lingual riband that reaches 
to the first stomach; from its upper part spring two cloven, 
though apparently tubular, short tentacula, united at their 
origins but diverging to their points, marked with close-set 
lines and snow-white dots; the eyes are immersed in the 
centre of the bases of the tentacula, which give them an obso- 
lete appearance. 
This animal is an hermaphrodite with congression; the 
male organs are white, placed between the disks, close to the 
right side of the head, and composed of two processes ; the 
first is a moderately-sized, rounded, arcuated, conically pomted 
stylet, connected with a tubular cylindrical body reflexed at 
the margin; the second is a perfectly white thread-like fila- 
ment issuing therefrom: these appear to be the virile appen- 
dages; they are in continual motion, and perhaps act in 
concert, the one being the verge, the other an epididymis or 
spermatic cord: above them is the vulva combmed with the 
oviduct ; it is a long, conical, very white, tumid process, } an 
inch long, with a considerable orifice. Next to these on the 
same side, between the disks, extending nearly their entire 
length, is the splendid branchial plume, which m the animal 
observed measured nearly 2 inches in length, composed 
of two gently arcuated leaves, tapering from their bases to a 
pointed extremity; each leaf consists of about twenty-five 
linear vessels or processes, resembling a twisted cord with 
a longitudinal depression in its centre, which is the bran- 
chial artery, and crossed on each side by transverse lines ; 
these cord-like fillets are closely packed together and taper to 
