PROFESSOR OWEN ON MACROPUS. 419 
concave lengthwise, through the descent of a postglenoid process (ib. figs. 1, 3, pq), in- 
ternal to which is a perforation. 
The alisphenoid (ib. fig. 3, #r) sends down a process (ib. fig. 1, 6') abutting against 
the paroccipital (4). The three compartments of the cranial cavity—epencephalic, 
prosencephalic, and rhinencephalic—succeed each other lengthwise’; and the olfactory 
cavity extends backward both above and beneath the rhinencephalic fossa. The “sella 
turcica” is indicated by the entocarotid foramina’, not by clinoid processes. The basi- 
occipital (ib. fig. 3, 1) is hexagonal, the hind border emarginate, forming the lower 
fourth of that of the foramen magnum (ib. fig. 4, 0) and contributing a very small part 
to each condyle (g). The exoccipital (ib. fig. 4, 2) develops the rest of that joint- 
surface (7), which is oblong-convex, with an upper or back portion bent at a right angle 
to the rest of the convexity. In young Macropodide the superoccipital (ib. fig. 4, 3) 
contributes a small share to the upper border of the foramen, which extends thereto by 
a fissure-like prolongation upward, between the then separate occipitals. These, 
however, by subsequent growth contract the fissure, and in adults of some large species 
obliterate it and complete the foramen by the exclusion of the superoccipital. There 
are two or more precondyloid foramina (ib. fig. 5, p), anterior to which is the vagal 
foramen (v), and next the larger single jugular notch (w), through which may be seen 
the hind end of the petrosal (16); this notch is usually completed, as a foramen, by the 
paroccipital process of the alisphenoid 6’, anterior to which the fore part of the petrosal 
is visible; but in some the union with the exoccipital (ib. 2-6) does not take place, 
and the whole extent of the basal part of the petrosal is seen; the junction of the ali- 
sphenoid (ib. fig. 1, 6') with the paroccipital (ib. 4) is constant and extensive. A smooth 
channel curves round the upper part of the condyle (ib. fig. 4, g) between it and the 
base of the paroccipital (4). The superoccipital (ib. fig. 4, 3) is octagonal, the upper 
and lower borders being the shortest ; the lateral ones next these above and below are 
the longest; the two outer sides are of intermediate extent. There are two rough 
oblong depressions (ib. 3,2) near the upper lateral borders, for tendinous attachments. 
Superiorly the superoccipital joins the interparietal (ib. fig. 2, 3), varying in shape and 
composition ; laterally it joins the parietal (7) and mastoid (8), and in some species 
1 The relative positions of the rhinencephalic, prosencephalic, and epencephalic compartments of the cranium 
are the same in lissencephalous (see Osteol. Collection, Mus. Coll. Chir. Sections nos. 2165, 2292, 2337, 2391, 
2407) as in lyencephalous Mammals; the compartment for the rhinencephala (“olfactory ganglions” or 
“bulbs” of anthropotomy), which compartment Prof. Flower terms “olfactory fossa,” is as much in front of 
the prosencephalic compartment or “cerebral fossa” in the Beaver and Agouti (no. 2051) as in the Wombat 
or Kangaroo, “The ‘olfactory chambers’ attain their maximum of deyelopment in some of the Porcupines 
(Hystriz):” Flower, Osteol. of Mammalia, 12mo, p. 153. Here the author means the fosse appropriated to 
the olfactory sense-organ. Those which lodge the divisions of the brain supplying the nerves of that organ, I 
had termed, to avoid confusion, “‘ rhinencephalic.” 
? Osteol. Catal. 4to, 1853, p. 323, no. 1735; this character is common to the order, see Art. ‘‘ Marsupialia,” 
Cycl. of Anat. (1847), p. 274. 
3L2 
