228 
TERTIARY VERTEBRATA OF THE FAYlTM. 
is strongly developed on the inner side of the cutting-talon, which is slightly notched in 
the middle. The talon of m. 1 is composed of an outer cusp, a very small posterior and 
a rather larger inner tubercle belonging to the cingulum, the three surrounding a 
shallow depression. The dimensions (in centimetres) of the teeth are : — 
Length. Width. 
w. B 1-9 1 
yn.2 1-8 '9 
mA FB -6 
M. 8873. Plaster cast of the above specimen. Made in the British Mnseyim. 
M. 8437a. Portion of right ramus of mandible with greatly worn and broken cheek-teeth. 
M. 8437b. Portion of right ramus of mandible with pm. 2 and 3 complete, the other cheek-teeth 
broken and worn. Figured on PI. XIX. fig. 4. 
M 8436. 
Posterior portion of right ramus of mandible with ?n. 2 and m. 3. 
fig. 5. 
Text-fig. 73. 
Figured on PI. XIX. 
I’ortion of right ramus of mandible of Apterodon macrotjnatlms ; A, from above ; B, from outer .side. 
pm. 4, fourth premolar; m. 1-3, tlie molars. | nat. size. 
The following specimens are referred provisionally to this species : — 
M. 8439. Nearly complete axis vertebra. In this vertebra the centrum is very mnch depre.ssed ; 
anteriorly its ventral surface is concave from side to side, but posteriorly there is a median 
keel terminating behind in a hypapophysis. The odontoid is much llatteneil dor.so- 
ventrally ; its ventral surface for the atlas is limited posteriorly by a sharj) ridgi'. 
Tbe lateral surfaces are about as deep as wide, their ventral borders being j)roduced 
downwards considerably below the ventnd surface of the nist of the centrum. The 
backwardly directed transverse [)roce.sses are largo and long, extending considerably 
behind the ])osterior end of the centrum ; the verh'brarteria! canal is small. The neural 
canal is both wid(! and high. The neural spine is a v('ry high hatehet-shaped plate 
projecting considerably backwairds behind the rest of tlu' vertebra ; its [)ost('ro-ventral 
bordi-r is much thickened. The posterior zygapophy.ses are massive projections, their 
