two new Species of Hectocotyle. 17 
or.whether they are to be regarded as animals quite different, and belonging 
perhaps to the class of Epizoa. According to my conviction the first is the 
correct view, which I hope best to prove by showing how I myself arrived at 
this conclusion. 
After I had concluded the anatomical examination of the two Hectocotyla, 
I for the first time entertained doubts of their relation to Epizootic worms, 
as for example Tristoma and Myzostoma, which they so perfectly resemble in 
their outward appearance, when I considered that not one of these worms, 
although not unfrequently provided with a highly developed vascular system, 
possesses two kinds of vessels, that is to say, arteries and veins, a heart and 
branchiz. Yet this alone, as may easily be believed, would not have been suf- 
ficient to induce an opposite conclusion, if other facts had not attracted my 
attention and compelled me to examine more carefully. In the first place, I 
was compelled to recognize the remarkable similarity of the Hectocotyle fur- 
nished with numerous suckers and violet pigment-spots with the arms of the 
Cephalopods on which they live; a similarity which extends so far that the 
suckers of Hect. Argonaute, with reference to the form and arrangement of 
the muscles, perfectly resemble those of the Argonaut, while those of the 
Hect. Tremoctopodis accurately represent those of the Tremoctopus; and the 
colour of the pigment-spots in each of the two animals belonging to each 
other perfectly coincided. Continuing to meditate on the subject, I called 
to mind several other points of agreement. First, the spermatozoa of Hec- 
tocotyle, which (like those of Sepia, Octopus, &c.) are furnished with a mode- 
rately long cylindrical body and a long filiform appendage; and secondly, 
the contractile pigment-cells, which occur in Hectocotyle exactly as in the 
Cephalopods, which is the more important, inasmuch as these remarkable 
cells have hitherto been found in no other animals. Lastly, I discovered the 
interesting fact, that the fibres which form the muscular mass of the arms of 
the Cephalopods are arranged in exactly the same complicated manner in 
three layers as those which form the muscular envelope of the body of the 
Hectocotyle. 
All these facts at length led to the conviction that there existed a remark- 
able agreement between the Hectocotyle and their Cephalopods; and the 
more I considered the subject, the more I felt compelled to believe in a cer- 
VOL. XX. D 
