210 
NOTES AND MEMORANDA. 
edge, the direction of the same being constant. In fact, the sections 
belonging to this zone may generally be distinguished at the first 
glance in a thin plate, and they strike the eye by their characteristic 
elongation and the known relation of this elongation to the facile 
sections. 
M. Levy has determined under these conditions the angles of the 
depolarizing axes of pyroxene, diallage, amphibole, epidote, sphene, 
and orthoclase, and has determined in tri clinic feldspars that some 
specimens belong to oligoclase and some to labradorite. 
The Badiolaria . — To all who are interested in this group may be 
commended the perusal of Mr. St. George Mivart’s paper, which is 
printed in No. 74 of the ‘ Linnean Society’s Journal’ (Zoology). 
The paper, though headed “ Notes touching Recent Researches on the 
Radiolaria,” is in reality a condensed treatise on the group ; and, whilst 
constituting somewhat of an innovation upon the usual practice of 
learned Societies, will be generally thought to establish a valuable pre- 
cedent, and one that might be very usefully followed with other subjects 
and in other Societies, particularly where, as is the case with the 
Radiolaria, the results of their investigation are for the most part locked 
up in a foreign language. Mr. Mivart thus prefaces the paper : — “ The 
example which has been set by our President in publishing from time 
to time in his successive addresses a digest and resume of the most 
recent researches which have been carried on respecting certain of 
the lowest animal groups, has led me to believe that a similar course 
might advantageously be taken with respect to the Radiolaria. Our 
publications already afford, through Dr. Allman’s recent labours, the 
readiest means of obtaining a knowledge of the most modern investi- 
gations with respect to various groups of Protozoa, and I have myself 
found the memoirs referred to most valuable and useful. I hope 
that other Fellows may adopt a similar course, so that our journal 
may become a complete repertory of information respecting all the 
lower groups of the animal kingdom. No English publication on 
the Radiolaria exists to my knowledge, and, although the most 
admirable monograph of Professor Haeckel was at the time (1862) a 
complete and exhaustive account, yet were it even readily and 
generally accessible, important additions have now been made to our 
knowledge of these animals since its publication. I venture to think 
therefore that an account of these beautiful, and in many respects 
complex organisms, will not be an unwelcome addition to English 
zoological literature.” 
The paper commences with a general descriptive account of the 
Radiolaria, followed by observations on their impressionability, loco- 
motion, and nutrition ; reproduction and growth; zoospores (with and 
without crystals) ; modes of growth ; distribution ; classification, and 
literature. 
In concluding the descriptive part of his subject, the author says 
that “ to his mind it seems evident that these beautiful symmetrical and 
complex forms cannot be due to the action of natural selection, and 
sexual selection can of course take no part in forming such organisms 
as these. Wo seem here to have forced upon our notice the action of 
