128 Progress in Science. [January, 
origin, that a specimen of Lingula ovalis, a shell of the Kimeridge clay, has 
been examined by him, so that the beds reached are already below the Purbeck. 
He remarks that the great upper clays of the oolites have been touched 
without encountering shore sands or shelly oolites,—no Portlandian rocks 
have appeared. Clay deposits may be found for a considerable depth; there 
may be no triassic beds, and he thinks that the paleozoic rocks may be reached 
at no enormous depth, and with no unusual difficulty. 
Mr. Whitaker has recorded the discovery of Thanet Sand on the northern 
outcrop of the London Basin, near Sudbury, where it had not previously been 
observed. 
Palzontology.—Dr. Von Mojsisovics has published the first part of his 
geological investigation of the neighbourhood of Hallstatt, in which he 
describes the remains of Cephalopoda obtained from the Zlambach and 
Hallstatt beds. He indicates repeatedly, especially in connection with the 
genera Lytoceras, Pinacoceras, Sageceras, and Arcestes, that he can by no 
means arrange the Goniatites as a distin& generic series in opposition to the 
Ammonites. The triassic representatives of the above-mentioned genera are 
most closely related in all essential peculiarities of organisation and habit to 
Goniatitic predecessors; the Ammonites from the Permian sand-stone of 
Artinsk, Waagen’s Permian Ammonite from the salt range of the Punjab, and 
certain triassic forms partially bridge over the gap which still exists between 
the older Goniatites and the Ammonites of the Trias. By far the greater part 
of the genera of Ammonites occurring in the Alpine Trias have their roots in 
the Palzozoic Goniatites ; and some of them may apparently even be traced 
back into the Upper Silurian formations. The greater part of these Paleozoic 
genera become extiné& in the Upper Trias, when they attain the height of 
their development, but at the same time show signs of senile degradation, 
analogous to the phenomena observed during the gradual extinction of the 
later Ammonitic types in the Cretaceous period. 
Professor W. H. Flower has described a new species of Halitherium from 
the Red Crag of Suffolk. It is of especial interest as furnishing the first 
recorded evidence of the existence in Britain of animals belonging to the order 
Sirenia. This new species presents many characters common to the Manati 
and the Dugong. 
PHYSICS. 
Microscopy.—A new freezing microtome, for facilitating the cutting of thin 
sections of soft tissues, has been contrived by Dr. William Rutherford, Pro- 
fessor of Physiology in King’s College, London. The construction of the 
machine will be easily understood by reference to the cuts. Fig. 2: A, hole in 
the brass plate (B); c, tube; D, screw; E, indicator; F, screw for fixing the 
machine to a table; G, box for holding the freezing mixture; H, tube for per- 
mitting the water to flow from the melting ice. Fig. 3: Vertical section. 
The hole A is shown containing a piece of tissue, and the box G containing the 
freezing mixture; K, a movable bottom to the hole A; R, transverse section of 
the knife used in making the se@tions: the other letters the same as in Fig. 2. 
The tissue to be frozen and cut is placed in the tube (A). The section is made, 
as in the ordinary instrument for cutting wood sections, by gliding a knife 
horizontally through the tissue projecting above the level of the plate (Bs). 
The thickness of the section is regulated by the indicator (gE). The machine 
may be employed for two objeé&ts :—For cutting tissues hardened in the ordi- 
nary way, by chromic acid, &c.; and second, for cutting tissues hardened by 
freezing. The second method of using the machine will be more readily com- 
prehended after a description of the first, which is simply this:—Place a 
portion of hardened tissue in the hole a, and pour around it a mixture of 
paraffin (5 parts) and hog’s lard (1 part), melted by the aid of a gentle heat. 
Or the paraffin mixture may be first poured into the hole, and the piece of 
tissue afterwards introduced, and held in any desired position, by means of 
forceps, until the paraffin becomes sufficiently hard. In order that the paraffin 
may fairly support the tissue, it is necessary that the surface of the latter be 
