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PROCEEDINGS OF METROPOLITAN SOCIETIES. 319 
exclusively on the conformation of the cranium. Several additional 
indications of the inferiority of these animals to other mammalia 
were pointed out ; and it was noticed, for the first time, that the 
sutures of the skull do not become united with age, as happens with 
the rest of the class. A new genus of this group was characterized 
under the name of T’halacomys, founded on the Perameles lagotis, 
(Reid), all the incisor teeth of which are placed contiguously. In 
treating of the maxillary bones, Professor Owen took occasion to al- 
Inde to the celebrated Stonefield fossils, and to the opinions recently 
put forth respecting them by Professor de Blainville. He had ex- 
amined four specimens of rami of the lower jaw, whereas the emi- 
nent French zoologist was acquainted only with the cast or model ; 
and did not hesitate to pronounce them to have belonged to marsu- 
pial mammalia, from the circumstance of the rami of the jaw con- 
sisting of only a single bone; also from the form of the inferior 
condyle ; and from the fact of the molar teeth being rooted in their 
sockets by two distinct fangs. Mr. Martin then called the attention 
of the meeting to the fact, not previously noticed, of the last infe- 
rior molar of the two Mangaluys, or dusky-coloured white-eyelid 
Monkeys ( Circopithecus wthiops and fuliginosus, Auct.), possessing 
a fifth tubercle, as in the Macaci, Inui, Cynocephali, and also the 
Semnopitheci, and Colobi, whereas the other species of Cercopithecus, 
* as was well known, have only four tubercles to that tooth, as in 
man and the three genera of Apes. It was remarkable, also, that 
the facial angle of those two species was greater than in any other 
Cercopitheci, a further approximation to the Macaquio; and Mr. 
Martin concluded by proposing that the term Cercocebus, applied 
by the late Mr. Bennett to several of the larger Cercopitheci, which, 
however, presented no absolute distinguishing character,from the 
smaller ones, should be restricted to the two animals in question. 
In the discussion which followed, Mr. Blyth remarked another dis- 
tinction observable in the two Mangaluy Monkeys, which, though 
of little consequence, he deemed to be still worthy of mention: it 
was, that whereas all the Cercopitheci, as now limited, have the 
hairs on the upper parts grizzled or annulated with two colours, the 
same was not the case with the Cercocebi. Professor Owen then 
read a letter which he had received from Dr. Ouley, announcing the 
presence of a small but distinct ligamentum teres in the Coypu ( My- 
opotamus coypu_), which had been recently asserted not to exist. 
OcrozeR 23rd.—A letter was read by the secretary from M. Ju- 
lian Desjardins, the secretary of the Natural History Society of the 
Mauritius, announcing that he would embark for England on the 
Ist of January next, with extensive natural history collections, 
which were partly intended for the museum of the Zoological Soci- 
ety. Another was also read from Col. Campbell, dated Alexandria, 
stating that he could succeed in attaining no additional information 
respecting the white African Elephants, which he had hoped to 
have forwarded. A third from Lieut. Col. Dogherty, the governor 
of Sierra Leone, who remarked that he shortly expected to obtain 
