367 
more like it than is that of Cereopsis (ib. fig. 7). It resembles more the latter 
Anserine in its complex ossification. Cnemiornis differs from both those genera and 
most other Anserines in the greater breadth of the cerebellar prominence (ib. 3) 
along the middle of the superoccipital tract, and in its greater slope forward as it 
rises from the foramen magnum (compare fig. 1, 3, with fig. 6,8, Pl. CI.). A narrow 
mesial tract slightly projects from the convex prominence in Cuemiornis; it answers to 
the sharper ridge (8) in Cereopsis (ib. fig. 7,3). The foramen magnum has a rela- 
tively longer vertical diameter in Cnemiornis than in Cereopsis or Tachyeres. In the 
yertical extent of the basioccipital', beneath the condyle (ib. fig. 7), Cereopsis comes 
nearer to Cnemiornis than does Tachyeres. A greater proportion of the parieto-frontal 
expansion of the cranium appears in the direct back view of the skull in Cereopsis than 
in Cnemiornis—the brain being smaller relatively, and the muscular impressions more 
extensive, in the larger extinct Anserine. 
The extent of the insertion of the portion of the “longus colli posticus” (ante 
pp. 47, 283, Pls. XI, & XII. o**), impressing the sides of the cerebellar protuberance, 
and leaving a convex ridge on each side the mid tract, dividing the occipital from the 
parietal surface, gives greater breadth to the upper part of the occiput, so defined, in 
Cnemiornis than in Cereopsis; the insertions of the “complexus” (p, 49, Pls. XI. 
XIII. y) leave the deeper impressions (Pl, CI. fig, 2,7 y) bounded by the lateral ridges ; 
and these are more distinct from the “ biventer” impressions than in Cereopsts. 
The basioccipital protuberances (ib. figs. 2, 4,1") are more developed than in any 
known Anserine, though they are well marked in Cereopsis (ib. fig. 7, 1') and indicate 
great size and power of the “recti capitis laterales” muscles (ante p. 50, Pls. XI. 
XIV.d). In the deep chink-like fossa between the protuberances and the paroccipitals 
open the canals giving passage to the hypoglossal and vagal (fig. 2, v) nerves and the 
paroccipital foramen (ib. p) (perforating the base of the paroccipital and opening into 
the tympanic cavity). The paroccipitals (figs. 1-4, 4), giving insertion to the “ trachelo- 
paroccipitales” (P). XII. fig. 1, 2), are subcompressed, and do not descend below the 
basioccipital protuberances. 
The basisphenoidal fossa (Pl, CL. figs. 4 & 9, 5), the floor of which is formed by a 
short triangular lamelliform process, receives on each side a (vascular t) canal from 
the tympanic cavity. On each side of the fore part of this fossa the entocarotid canals 
(ib. ib. ec) are exposed in Cnemiornis, which converge to terminate at the back part 
of the deep “sella.” Of these canals there is only a minute indication in Cereopsis. 
In advance of them the basisphenoid contracts and develops the pair of pterapophyses 
(ib. ib. 5’), here, asin other Anserines, well marked, but sessile; they are a long ellipse 
in shape. : ' ' 
The base of the alisphenoid swells out, external to the entocarotid opening, to 
‘ The “fontanelles ” * due to original arrest of ossification between the exoccipital aud mastoid” (Anut. of 
Vertebrates, tom. ii, p. 49), are obliterated in both Onemiornis and Cereopsis. nat 
. oM 2 
SO =p eee ee eee 
