NOTES AND MEMORANDA. 
209 
Glyciphagus plumiger. — In ‘ Science-Gossip ’ for July, Mr. A. 
Michael mentions the capture by him of this acarus in England, in 
fodder in a stable. Though only one other case of its capture here is 
on record, Mr. Michael considers that from the fact of it having been 
found in two remote parts of the country, between which there would 
not be likely to be communication, and which are both agricultural, it 
may be fairly claimed as a British species, although only a single 
individual has been detected in each instance. A woodcut of the female 
(not previously figured) is given. 
A New Family of Calcareous Sponges. — Mr. H. J. Carter describes, 
in the ‘ Annals ’ for July, two new species of calcareous sponges, in 
which the excretory canal-systems do not open into a common cavity 
(the “ cloaca ” of Dr. Bowerbank) which discharges itself at one or 
more apertures, but open directly upon the surface. 
Mr. Carter gives the following description of the single genus of 
the family : — 
Teichonellidao (reixog, a wall), new family. Character. — Vallate. 
Teichonella, nov. gen. 
Generic characters. — Vallate or foliate, without cloaca. Vents 
numerous, confined to the margin, or general on one side of the lamina 
only; naked. 
Both the species T. prolifera and T. labyrinthica (which are de- 
scribed at length and illustrated in a plate of nine figures) are in the 
British Museum — the former (which is by far the largest Calcisponge 
on record) for many years and the latter (only second to it) were in 
Dr. Bowerbank’s collection purchased by the Museum. Deferring to 
Professor Haeckel, Mr. Carter considers it “ somewhat laughable that 
the self-constituted author of ‘ The History of Creation ’ should have 
omitted a whole family of the Calcispongiae.” 
The Polarizing Microscope in Mineralogy. — At the session of 4th 
February last of the French Academy of Sciences, a note by M. A. 
Michel Levy was presented by M. Des Cloizeaux, on the use of the 
polarizing microscope with parallel light for the determination of the 
species of minerals found in thin plates of eruptive rocks, by means of 
the depolarizing axes which the crystallized elements of these minerals 
evince in parallel light between two crossed Nicols. 
The crystallographic orientation of these elements is generally 
indeterminate, and the employment of the polarizing microscope with 
parallel light is alone possible on account of the minuteness of the 
crystals and the extreme tenuity which must be given to the plate to 
render it sufficiently transparent. But these inconveniences are com- 
pensated by the large number of crystals which can be operated upon, 
and by the elongation which certain species assume in a particular 
direction. 
M. Levy proposed to study the variations in the position of the 
depolarizing axes of a given mineral with respect to the different 
sections which were produced parallel to its edge of elongation, by 
finding the angle of each position of the depolarizing axis with that 
