ON SOME NEW AND LITTLE KNOWN CREODONTS. 
IKO 
tions.,r,- Slmi"ht .md show no umlnlations, except the small ciitved frontal gyms, 
•riie eercliellum is large, being l.roader than the hemispheres; the vermis is rather 
narmiv and not very prominent, but the lateral portions are very large and obscuiely 
convoluted. (Sec I’l. VII, Fig. 4). , m „ ■ r 
The brain of II. horrklm is strikingly small when compared with the size of the 
skull : it is proportionally but slightly longer than the brain of Thylacjjnm, and not 
quite so broad; the latter also shows considerable similarity in the pattern of the con- 
volutions, though these are very obscure in a cranial cast. (See Gervais Nouv. 
Arch. d. Mus., t. v., I’l. XIV, Fig. 5). 
Thus Gervais’s specimen is seen to differ from the American species in shape, in 
the much narrower cerebellum, and in the character of the convolutions. 
Skf:i,eton.-:-A most important and valuable specimen of H. horrklus, belonging 
to the Museum of Comparative Zoology, has been very kindly sent to me by Professor 
Agassiz. This specimen, I think, will decide the disputed question as to the syste- 
matic jiosition of this curious genus. 
The adds has rather small transverse processes, which do not seem to be pierced 
by the vertebral canal ; the superior and inferior arches are slender. The axis is in 
some rcsiKJcts like that of Mesonyx ; the centrum is broad and much depressed, with a 
strong keel ; the atlanteal faces are narrow, transversely directed and not emarginated 
by the neural canal, which is small ; the transverse processes are long, stout and per- 
forat(Hl at the base ; the spine is high and thin, and posteriorly forms a stout rod which 
])rojccts to the 4th vertebra ; this rod is horizontal instead of oblique, as in Mesonyx. 
\ somewhat similar arrangement is seen in Lutra. This specimen shows clearly that 
tlie axis doubtfully attributed to Hyamodon by M. Gaudry (Ench. d. INlonde Anim., 
fig. 9) must belong to some other genus. No resemblance to the opossum’s axis is to 
lx; found in the specimen before us. The other cervical vertebrae are rather long, with 
opistluKJcelous centra, and large, very oblique zygapophyses ; the spine of the 3rd is a 
low ridge, that of the 7th long and stout; the others are too much broken for deter- 
mination. 
The dorsal vertebra;, of which the anterior seven are represented, hav^e rather 
sliort, heavy and depressed centra, and very strong neural spines ; but, as none of the 
latter are complete, their length cannot be stated; all the spines incline strongly 
backwards. 1 he first dorsal is remarkable for the large size of the transv^erse process, 
and its strongly concaA e facet for the tubercle of the rib ; the second has a similar but 
somewhat smaller process, and in the other vertebrae the process becomes of the ordi- 
nary size, though conspicuous in all. In proportion to the size of the skull, these 
vertebra* arc larger and have heavier processes than those of Mesomjx, indicating a 
more jOTwcrful animal. 
Of the Inmlmr scries five are preserved; they have very large centra which are 
)road, depressed, slightly opisthoccelous and, except the last, provided with keels ; the 
