154 Macteay Memorrat Vouume. 
of short, sub-cylindrical tentacles, and behind these are five more pairs of tentacles 
of relatively considerable length when fully extended, radiating outwards from the 
lateral margins of the body—the more anterior directed forwards as well as outwards, 
and the more posterior backwards and outwards. Behind, on the ventral surface, is 
a large circular posterior sucker situated close to the posterior end of the body, and 
in front, below and a little behind the head-lobe, is a smaller, pit-like, anterior sucker 
not raised above the general surface. The animal moves, exactly after the manner of 
a leech, by the extension and contraction of the body and alternate fixation of the 
suckers. These movements are as rapid as those of Zemnocephala or Craspedella. 
The tentacles are never employed in locomotion, and in fact I have never seen 
them being used in any way, though they may be observed to become extended and 
contracted and to undergo slight quivering movements: the probability is that they 
are only brought into play for the seizure of living prey. 
The aperture of the mouth is a slit situated some little distance behind the 
anterior sucker. There is a single genital aperture situated just in front of the 
anterior margin of the posterior sucker. There are no eyes. 
The body is completely devoid of pigment, but the internal organs are, 
nevertheless, very difficult to study, owing to the numerous bright granules which 
are scattered through the parenchyma. The whole animal is very much softer and 
more delicate than is the case with Zemnocephala—a very slight pressure serving to 
crush it. 
No observations were made on the nature of the food; the intestine was empty 
in all the specimens examined, or at least contained no recognisable particles, except 
in three, in each of which one of the Nematodes that infest the branchiz of the 
Engeus in large numbers had apparently been partially swallowed. I think it is 
extremely likely that Actenodactylus resembles Temnocephala in its mode of 
feeding ; its remarkable activity, the fringe of sensitive tentacles, and other features 
in its organisation yet to be described, seem adapted to such a mode of life. 
I1J.—Inrecument anp Muscuntar Layers. 
Actinodactylus resembles Temnocephala in having an integument (fig. 3) consisting 
of cuticle, nucleated epidermal layer, and, perhaps, basement-membrane. Scattered 
over the surface along the lateral margins and on the tentacles are numerous 
elevations of a conical form, each with a group ef non-motile cilia similar to the cilia 
of the tactile cones of the Zemnocephalee, but relatively longer. Similar cilia not 
placed on cones occur in small numbers about the ends of the tentacles. There are 
