DR. T. S. COBBOLD, FURTHER OBSERVATIONS ON ENTOZOA. 351 
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obliquely in reference to the central line, the angle of divergence being about 25°. During 
the eversion and retractation of the claws, the vacant spaces directly above them dilate 
and contract, so as greatly to facilitate the prehensile action of the hooks. These de- 
pressions are obviously inversions of the ventral integument, forming socket-like pouches 
for the implantation of the hook-capsules. If one of the claws be isolated and viewed 
laterally, it will be seen to consist of two parts — namely, a strongly curved hook (a, fig. I), 
and a cajisule (b). The upper part of the latter forms a hood ((/), for the lodgement, 
support, and protection of the hook ; the lower tubular portion serving to fix the apparatus 
in the body, and at the same time to regulate the movements of the claw through the 
intervention of a muscular pulley (g), which enters the tube at the lower end. Acting 
antagonistically to this, we find an extensor muscle (/) inserted into the anterior border 
of the base of the hook itself. The summit or projecting point of the hood is flattened 
out, so as to form a three-cornered process (e), which covers and protects the -harp ex- 
tremity of the hook when the latter is retracted. 
In regard to other external appearances, my observations for the most part correspond 
with those already on record; but with reference to the rows of minute integumentary 
spines, it will be seen from my figure (3), that the uppermost row is placed somewhat 
more apart from the second— at least, at the sides ; the whole forming a complete and 
graceful tracing, as it passes downwards on either side between the inferior and superior 
pair of cephalic claws. Further, I do not find the spines themselves to be simply conical, 
as hitherto represented, because their uniformity of outline is interrupted at the lower 
third, as shown at the left margin of figure 5 ; this appearance, indeed, can only be seen 
by a lateral view. The so-called stigmata (Athemlocher of Xordmann) display a double 
outline, but no vessels could be traced in connexion with them. 
With respect to the internal structure of this parasite, very little can be made 
circumstance materially favouring the notion that we have to deal with an imperfectly 
developed animal. Throughout the body there exists a central clear space, and this is 
well defined by dark lateral masses, which narrow out on either side of the head, in the 
form of a horse- shoe-shaped band enclosing the mouth and the four ehitinous claw-ma - 
These dark patches at first sight look like albumenogene organs, 
turn shows that they are entirely made up of large parenchymatous cellules, unconnected 
. any special fibres or tubes. In an isolated and highly magnified group of them, 
the granular contents and central nuclei at once became visible, as represented m fig 6, 
but 
where some have become flattened at the sides from accidental pressure . 
Before finally quitting the consideration of this parasite, I may advert to the recently 
advanced opinion of Gurlt, Kuchenmeister and others, respecting its assumed larval con- 
dition. After the perusal of Leuckart's original memoir t, kindly placed n my hands by 
Mr. Busk, I naturally felt desirous of repeating that extinguished zoologist s experiments. 
Accordingly (as I have alreadv stated in the Quart. Journ. Micr. Sc), on the 11 ho Jfe- 
bruary, I proceeded to infest two dogs. Into the nostrils of the first hound, stated to be 
* Leuekart, in his recent work, « Bau und Entwickelungsgeschichte der Pentastomen,' says they are glandular, and 
with 
t 
See also my translation in the ' Micr. Journal,* vol. vii. p. 182. 
