A NEW CUTANEOUS PARASITE, THE ENTOZOON FOLLICULORUM. 
311 
while the latter directs the middle piece nearly horizontally backwards, and converts 
the posterior projecting angle into a receding angle. The capsular membrane of this 
articulation during the movements of the segment, is raised into a fold on the side 
corresponding with extension, and reminds one very forcibly of the analogous manner 
of articulation of the crural segments in the Lobster. The third segment is short, 
and admits at a very trifling extent of movement on the extremity of the middle piece. 
It is flat on its distal surface, and provided with seven or eight digital processes or 
phalanges, which during the movements of the limb, are one while drawn together 
and straightened so as to have the appearance of a single conical point, and another 
while separated and curved, so as to resemble a number of hook-shaped claws. The 
latter is their more frequent condition. 
The contents of the thorax are very indistinct, on account of the general transpa- 
rency of the animal, and I have been quite unable to detect anything like a proper 
organ. On two occasions I saw some granules rising and falling in a central direc- 
tion, being bounded on each side by a faint longitudinal line; this I conceived to be 
some alimentary substance moving in the oesophagus. The difficulty of perceiving 
any organ within the thorax is moreover increased by the presence of numerous adi- 
pose vesicles which constitute the subtegumentary tissue. On bringing the interior 
of the thorax to a focus, some faint waving lines may be seen along the sides of that 
cavity; these are the muscles of the legs, and they are continuous with the retractor 
muscles of the head ; the latter appear to be attached to two ridges which project 
from the upper and lateral part of the two first thoracic segments. In the upper and 
anterior part of the thorax I have observed pretty constantly a transparent spot that 
seems to be an unoccupied space, bounded by the substance of the animal below and 
by the vaulted transparent integument above. This space has reference to the retrac- 
tion of the head within the thorax. 
The abdomen is the largest of the three divisions of the body, usually several times 
longer than the thorax, but somewhat smaller in diameter at its commencement than 
the latter, and tapering more or less to its termination. Its form is that of a cylinder 
slightly compressed from above downwards, being flatter on its under than its upper 
surface. The integument of the abdomen is composed of narrow annular segments 
which overlap each other from before backwards, and become narrower towards its 
extremity. These segments have a beautiful appearance when seen with the micro- 
scope, and give the idea of an exceedingly delicate coat of plait armour. When 
examined along the edge of the abdomen they exhibit a serrated outline, the serra- 
tions being sharp and accurately defined. Upon the under surface of the abdomen, 
close to its extremity, is a small opening which sometimes appears circular and some- 
times elliptical in shape, the long diameter of the ellipsis being directed transversely ; 
this is the anus. 
The segmented structure of the abdomen permits of flexion of this part of the 
animal in every direction, namely, forwards, backwards, and laterally. Indeed, when 
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