Royal Institution. 333 
sacral vertebree are shorter and thicker, and abut against the ossa 
innominata, as far back as the ischial tuberosities. The ilium, 
ischium, and pubis have coalesced to form one bone, as in some 
lizards and in mammalia; and, as in the latter class, the symphysis 
at which the ischio-pubic portion of each os innominatum joins its 
fellow is continuous; the pubic symphysis is not separated from the 
ischial symphysis. But ossification has advanced further than in 
any mammal, to the complete obliteration of the obturator foramina, 
which in most reptiles are represented by very wide vacuities. The 
pubic bones show an oblique perforation near the acetabulum, homo- 
logous with that which co-exists with large obturator openings in 
most lizards. The brim of this singularly massive pelvis measures 
10 inches in antero-posterior, and 1] inches in transverse diameter : 
the outlet measures 4 inches in antero-posterior, and 9 inches in 
transverse diameter. 
In the comparison of this, at present, unique type of pelvic struc- 
ture, it is interesting to observe, in connexion with the mammalian 
tusks in the skull, a mammalian condition of the symphysis pubis, 
and also a mammalian expansion of the iliac bone. In the number 
of sacral vertebrae Dicynodon resembles the Dinosaurian reptiles, as 
well as some mammalia; and hence it may be inferred that, like the 
Megalosaurus and Iguanodon, a heavy trunk was in part supported 
on a pair of large hind limbs, the weight thereupon being transferred 
by a larger proportion of the vertebral column than in the prone 
crawling crocodiles and lizards of the present day. 
The author, from certain associated fossils, deduces a probability 
of the triassic age of the sandstones including the above-described 
South African Reptilia, and remarks that it is in a sandstone of triassic 
age in Shropshire where fossil remains occur of a reptile which, in 
biting with trenchant edentulous jaws, also pierced its prey by a 
pair of produced weapons analogous to the tusks of Dicynodon. Of 
this reptile, the Rhynchosaurus artieeps, Ow., the author describes 
the skull, vertebree, and some other bones, which have been lately 
discovered in the New Red Sandstone of Grinsill, Shrewsbury. The 
remains of the limb-bones in this specimen bespeak a reptile capable 
of progression on dry land, as well as of swimming in the sea—of one 
that might leave impressions of its foot-prints on a tidal shore. 
ROYAL INSTITUTION OF GREAT BRITAIN. 
Friday, March 7, 1862. 
*On the Distribution of Northern Plants.” By Professor D. 
Oliver, of University College, London. 
The discourse referred primarily to the botanical evidence bearing 
upon the hypothesis advanced by Professors Unger* and Heer+ of an 
Atlantic communication between Europe and America at some period 
of the tertiary epoch. The close analogy which is to be traced 
between the miocene flora of Central Europe and the existing flora of 
* ‘Die versunkene Insel Atlantis.’ tT ‘Flora Tertiaria Helvetie.’ 
