TERTIARY VEITTEBRATA OF THE FAYtM. 
2 OS 
anterior cd<;-c of the maxilla. 'I'lie canine, which was about the same size as the 
incisors, is separated from i. o by an interval of about '7 cm. ; behind it again there is 
a diastema of about 2 cm. se])arating it from a single-rooted tooth, behind ■which 
again, and separated from it by a short interval, are four closely crowded alveoli. From 
the examination of this specimen alone, in which the teeth themselves are wanting or 
represented by their roots only, one would come to the conclusion that these four 
posterior alveoli belonged to the single-rooted ])m. 2, 2 )>n- 3, and a double-rooted yjm. 4, 
as they have been marked in the figure ; but Dr. Abel, who has better specimens in which 
the teeth are preserved, states that in Eotheriuvi the posterior premolars are single- 
rooted, and that there are in all six premolars, of which the second is lost very early. 
If this be so, then the alveoli marked yun. 4 in the figure belong to j^m. 5 and 6; 
those marked pm. 2 and^uH. 3 to ynn. 3 and/jni. 4, while between the 2 and jim. 1 
of the figure a tooth has been lost and its alveolus disappeared ; it may, how’ever, be 
remarked that there is only a very short diastema behind pm. 1, wdiile the interval 
between it and the canine is considerable, so that if a premolar has been lost at all it 
seems more likely to have been the first of the series. It is possible that the skull 
here figured may have come from a rather higher horizon than that at which Eothcrium 
})ropcr is found, and that some modification of the teeth in the direction of the later 
forms may already differentiate it from the animal described by Abel; possibly it may 
belong to Abel’s new genu$ Frofosiren*, at present undefined. Until that ^Ariter’s 
work on these Middle Eocene Sireniaus is published, these questions must remain 
undecided. The molars are three in number ; they are bilophodont teeth, the anterior 
crest being formed by a large blunt inner cusp and an outer sharper portion composed 
of two obscurely separated elements. The posterior crest also consists of a blunt 
inner tubercle and a shar])er outer one. From the antero-external side of the antero- 
internal cus]i a ridge runs down to the cingulum, which forms a small slndf-like 
projection on the anterior face of the tooth : from the postero-external face of the 
postero-iuternal ensp a similar ridge runs down to the cingulum of the posterior end 
of the tooth ; this ridge is best develo])cd in vi. 3, where, w-itli the main inner cus]), it 
gives a V-shaped surface in wear. 4'his type of tooth agrees with the description given 
by Dr. Abel f of the primitive Sireniau molar, except that the intermediate cusp of the 
hinder row is very obscurely developed, if at all. 
The dimensions (in centimetres) of this skull are : — 
Extreme length (exaggei'jited by fractures) ',](]•') 
Width between outer anghis of occipital condyles .... 8-2 
Greatest width of occipital surface 18 
W'nhh oi' foramen riuy II u III 4 
Height of occipital surface above /ovu/aeu iniijninn .... 7‘2 
* Abel, op. cit. p. 14G. 
t Abel, op. cit. pp. Tlo-JG. 
