two new Species of Hectocotyle. 15 
new series of the ‘Annales des Sciences Naturelles, page 185, under the title of 
Prétendu parasite de ľ Argonaute. According to his opinion the animal is only 
a part of the Argonaut, perhaps a spermatophore, of a singular shape. Accord- 
ing to my own opinion, which will be explained hereafter, the body discovered 
by Delle Chiaje and Costa is indeed a distinct animal, and, as I hope to be able 
to prove, most probably the male of the Argonaut. As this animal is very like 
the Hectocotyle of the Tremoctopus in its exterior shape and structure, I pro- 
pose to give only a brief account of those points in which they chiefly differ. 
The Hectocotyle of the Argonaut is worm-like, 7 lines long and 3 a line in 
breadth, thicker in its posterior than in its anterior part, and provided at the 
latter with a filiform appendage 6 lines in length. "The ventral surface of the 
body is furnished with two rows of suckers alternately disposéd, forty-five on 
each side; the dorsal surface is smooth, without branchiz, but provided in its 
posterior part with a great many round or elliptic spots of a red or violet 
colour. The appendage is thickest at its origin, and gradually decreases till it 
becomes very small. In two of the three animals which I obtained, the end 
of this appendage was quite free; in the third one I found it fixed to the pos- 
terior part of the body, that is to say, the end of the process pierced through 
an opening in the back, just at the part where the coloured spots commenced, 
and was connected with the male organs in a manner which I shall hereafter 
describe. Attached to the superior surface of the appendage, close to its 
junction with the head of the animal, are two delicate triangular membranes, 
one on either side; they are connected to the appendage by one side, the other 
being free. 
The structure of the animal is very similar to that of the Hectocotyle of the 
Tremoctopus. 'The skin, the contractile coloured spots or pigment-cells, the 
muscular envelope of the body, the structure of the suckers, are nearly alike 
in both, size alone excepted. I found however only one large vessel on each 
side, and instead of branchiz a great multitude of capillary vessels in the fili- 
form appendage and in the skin of the dorsal surface. I could not detect a 
heart, nor was I able to find either nerves or organs of sensation. The intes- 
tine, which commences with a small orifice just beneath the basis of the 
appendage, could be traced through the whole body, but no anal opening was 
to be found. 
