xiv Transactions of the Boyal Society of South. Africa. 
An exhibition of skulls of Trematosaurus and Rhinesuchus was given 
by Mr. S. H. Haughton. 
Bhinesuchus tvhaitsi and Trematosaurus soheyi are both members of 
the group of Temnospondylus Amphibians, and are from the Karroo beds 
of Cape Colony — the former from the lower Beaufort beds of Beaufort 
West, and the latter from the Burgersdorp beds of Queenstown. These 
skulls are two of the first Labyrinthodont skulls known from South Africa, 
and add considerably to our detailed knowledge of the group as repre- 
sented in this country. 
Bhinesuchus is closely allied to the American genus Eryops, and is 
particularly interesting in that, besides having a row of maxillary and a 
row of palatal teeth, it has the prevomers, pterygoids, and part of the para- 
sphenoid covered with small denticles. A species nearly twice the size is 
known from the Karroo beds of Senekal, O.F.S. 
Trematosaurus was previously known by one small species from South 
Africa, and a slightly larger one from the Triassic rocks of Germany. 
From this skull the palatal details are being described for the first time. 
An exhibition of the burrowing prawn Upogeoia captensis was given 
by Mr. K. H. Barnard. 
Members of the family Gallianassidae are found all over the world, 
burrowing in sand and mud. The present specimens were found burrow- 
ing in a hard, indurated sandstone, which seems to be the first record of 
such a habitat. It is difficult to conceive how the burrow is made. 
Papers : — 
"The Great Dyke of Norite of Southern Rhodesia — Petrology of the 
Selukwe Portion," by A. E. V. Zealley. 
The well-known great dyke of Southern Rhodesia extends for some 
300 miles throughout the Territory, and has a width of outcrop of about 
4 miles. It has usually been regarded as composed of ultra-basic rock such 
as picrite. ' 
The author, however, takes the view that it should be termed a dyke 
of Norite. The dominant rock types which make up the intrusion are 
felspar rich norite, enstatite and enstatite peridotite. These outcrop in 
elongated strips or wedges parallel to the edges of the intrusion, the less 
basic types which are also the finest textured forming the innermost strips. 
Various theories have been put forward with regard to this intrusion. An 
intrusion made up of rocks outcropping in this manner may be a dyke or 
a sill or a laccolite. 
The author's view is that in general the intrusion has many of the 
characters of a dyke, thus its rectilinear outcrop, the parallelism of its 
sides and fairly constant width (which is small in comparison with its 
longitudinal extension), together with the symmetrical disposition of the 
variations, indicate a dyke rather than a sill or laccolite. 
