10 Prof. Köker on the Structure of 
Description of the Hectocotyle of Tremoctopus violaceus. 
1. External Form. 
This animal very much resembles the Hectocotyle Octopodis, which Cuvier 
has described in the ‘ Annales des Sciences Naturelles’ for the year 1829*, the 
anterior part of the body being long, worm-like, and provided with two rows 
of suckers on its ventral surface, the posterior short and of an oval shape; 
but independently of its being much smaller, it differs also at first sight from 
H. Octopodis in the back being fringed with à great number of little branchial 
appendages,.and the posterior extremity having a long process. 
The anterior part of the body varies in length from 13-12 of an inch, is 
thickest in the middle, and diminishes towards both extremities. Without 
the branchiz and suckers it would be nearly cylindrical, but in the natural 
state the cephalic portion is almost quadrangular, while that immediately 
behind is flat, and has sharp margins. Its colour is almost entirely pure white ; 
it exhibits however at the branchize some azure tints, and here and there some 
yellowish hues; there are also some remarkable spots on the back, of which [ 
shall speak presently. The upper surface of this anterior part bears in its 
cephalic portion the branchial appendages and the spots just mentioned ; the 
upper surface of the posterior portion, on the contrary, is perfectly smooth ; 
the spots are arranged in two slightly-irregular rows between the branchize 
along the middle of the back; they are circular, about 4th of a line in 
diameter, of a brown or violet colour, and about 50 in number. The branchial 
appendages are placed on a low, mantle-like margin, which takes its origin 
from the side of the animal between the suckers and the coloured spots; the 
appendages have a conical form, are 1 line long and ith of a line broad: 
during life those next to the middle of the back stand vertically erect, the 
others successively assume a more inclined direction, 
and the outermost lie 
neatly transversely. The appendages are disposed in irregular longitudinal 
lines; their number is considerab 
le, amounting to about 250 on each side. 
The ventral surface of the anterior part is quite smooth in the middle, and 
slightly convex from side to side; on each of its margins are situated 40 or 41 
* lre Série, t. xviii. p. 147, 
