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POPULAR SCIENCE REVIEW. 
it presents no trace of structure. It follows the contour of the facets on the 
surface of the deeper layer. The deeper layer consists of numerous thin 
laminse, each being composed of a vast number of parallel fibres. It further 
appears to consist of hexagonal prisms, vertical to the surfaces of the cornea, 
and to the laminae of which it is composed. These prisms are not, how- 
ever, separable, although the laminae and the fibres of which they are 
composed are easily separated by treating the section for a short time with 
a solution of caustic potash. The surfaces of this deeper layer of the cornea 
may be seen to be covered with convex facets, a facet corresponding to 
either extremity of each vertical prism, the external facets being, however, 
best marked. In section this layer is seen to be marked by several hundred 
crenated lines, caused by the laminae of which it is composed ; the crena- 
tions follow the contour of the facets, the middle layers being almost or 
entirely without crenations. These lines, as well as the indications of the 
division of the cornea into hexagonal prisms, are best marked in the ex- 
ternal portion of the layer. Numerous minute nuclei appear between the 
laminae. When viewed by the aid of polarised light and a selenite, these 
modifications of structure all become beautifully apparent. Both layers of 
the cornea polarise, and the colour of the transmitted beam varies from 
red to green, according to the thickness of the section simultaneously in 
both.” 
How to Mount Spiders for Cabinets. — In M. Thorell’s fine 4to on European 
Spiders, which singularly enough is published in Upsala, and yet printed in 
the English language, the following instructions are given : — “ The spider is 
first killed, either by the vapour of ether or by heat, and is impaled by an 
insect-pin, which is passed through the right side of the cephalo-thorax ; the 
abdomen is then cut off close to the cephalo-thorax, and the cut surface dried 
with blotting-paper. The head of another insect-pin is cut off, and the blunt 
extremity introduced through the incision into the abdomen, up to the 
spinners. The abdomen thus spitted is inserted into a large test-tube held 
over the flame of a candle, the preparation being constantly rotated till dry, 
avoiding the extremes of too much or too little heat — the firmness of the 
abdomen being tested every now and then with a fine needle, till it is so 
firm as not to yield to pressure ; the front extremity of the pin is now cut 
off obliquely, and the point thus made inserted into the cephalo-thorax, the 
two halves of the body being thus again brought into apposition. The 
animal may then be mounted as usual.” 
Nero Tailless Batrachians. — At the meeting of the Zoological Society on 
June 9 l)r. A. Gunther communicated an account of the species of tailless 
batrachians recently added to the collection of the British Museum, 
amongst which wa9 a new diminutive frog, recently discovered by Dr. Cun- 
ningham in Fuegia, and proposed to be called Nannophryne variegata. 
African Swalloios . — At a meeting of the above-mentioned society on 
May 12 Mr. R. B. Sharpe read a paper containing a full account of the 
swallows ( nirvndinida ) of Africa, and pointed out their characters and 
geographical distribution. Particular attention was drawn to the affinities 
of the African Ilirundinida; with those of the New World, and also to the 
representation of various species by smaller races or sub-species throughout 
the ^Ethiopian region. Thirty-eight species of swallows were enumerated, 
