1864.] PROF. HUXLEY ON ARCTOCEBUS CALABARENSIS. 331 
The spleen (fig. 8) is 1°5 inch long and 0°3 inch wide in the middle ; 
it is very flat, and tapers to each end. It is attached by the lesser 
omentum to the cardiac end of the stomach, and does not extend along 
its great curvature. The alimentary canal thus much resembles that 
of the Potto (Van der Hoeven, /. c. pp. 50,51). In the latter, how- 
ever, the stomach forms a small czecal dilatation beside the pylorus, 
and the colon is sacculated, though the czecum is devoid of saccula- 
tions. Neither in the Potto, nor in Ofolicnus peli, nor in Tarsius, is 
there any appendix vermiformis, though Schroeder van der Kolk, 
and Vrolik find it to be represented in Nycticebus (Recherches 
d’Anat. Comp. sur le genre Stenops). 
The liver appears to be somewhat more subdivided than in the 
Potto, but not more than in Stenops (Sch. K. & V.). The ductus 
choledochus opens much nearer the pylorus than in either Tursius 
or the Potto, in which it ends in the descending part of the duo- 
denum. The pancreas is divided into lobes in Tarsius, Otolicnus, 
and Stenops (Schroeder van der Kolk and Vrolik). The spleen is 
confined to the cardiac end of the stomach, not attached along its 
greater curvature as in Tarsius, the Potto, Nycticebus, and Loris. 
The arterial part of the vascular system of the Angwantibo had 
been partially injected by Mr. Murray, with the view of determining 
the existence and the nature of any retia mirabilia which might 
exist. Mr. Murray was unfortunately prevented, however, from 
carrying his examination of the specimen, while freshly injected, 
further than the brachial artery, which, he writes, exhibited “a lon- 
gitudinally striated appearance. I meant to have dissected these 
striations fully and delicately out, and expected to find that they 
were composed of a series of vessels... .. I reasoned that it would 
answer the same purpose, whether the artery was broken up into many 
branches spread all about the arm, or packed in one tube...... 
When I last looked at it the striations were much less visible than 
at first. At first they were wondrous distinct.” 
Unacquainted with these observations, I, at first, nearly failed to 
make out the existence of any rete mirabile in either the upper or 
the lower extremities. | Occupying the place of the brachial and 
femoral vessels, I found what had all the appearance of simple 
trunks, filled evenly, though imperfectly, with the red injection-mass ; 
and it was only on finding myself unable to pass a fine style into the 
supposed arteries, that I was led to examine their structure more 
minutely by the help of transverse sections and the microscope. 
Each trunk now turned out to be a dense and firm cord of connective 
tissue, traversed longitudinally by multitudinous trunks, some of 
which presented the remains of the red injection, while the others 
were empty. The former and the latter occupied opposite halves of 
the cord, and were not intermingled. In the femoral cord, the in- 
jected trunks were one comparatively large artery, 2;th of an inch in 
diameter, with strong walls, and about eighteen smaller ramuscules of 
between a half and a third the diameter of the large one. The un- 
injected trunks were of a similar size. - 
