March 7, 1878] 



NATURE 



367 



peculiar structure project. These long hairs are very 

 thin at the bulb, and increase very gradually in thickness 

 for about one-third of their length, when they suddenly 

 contract a little, and then expand into a flat lance-shaped 

 blade, which terminates in a very fine point. This 

 coarser part covers the whole body, the thick root of the 

 tail, and the upper part of the limbs ; the rest of the tail, 

 the under side of the muzzle, and the upper surface of the 

 feet are clothed with short, close hairs. The ears are of 

 moderate size, the eyes very small, and the toes on all 

 the feet, five in number, are armed with small sharp claws, 

 and without webs, but the second and third toes on the 

 hind feet are united as far as the end of the first phalanx 



The most remarkable peculiarity of the animal is its 

 tail, which presents a most unusual development for an 

 insectivorous mammal. Prof. AUman says : — " It is so 

 thick at its base that the trunk seems uninterruptedly 

 continued into it ; but it soon becomes laterally com- 

 pressed, and then grows gradually thinner and narrower 



towards the tip Its lower edge is rounded, and its 



upper is continued into a membranous crest about one- 

 eighth of an inch in height, and clothed with the same 

 short, stiflF, appressed hairs " as the rest of the tail. 



This great development of the tail might of itself con- 

 vince us that this organ is of great service to its owner, 

 and such, from the account of the habits of the animal 



Fig. 3. — West African River Shrew {Potaiiwgale veio.v). 



given by its discoverer, is evidently the case. M. du 

 Chaillu says: — "This extraordinary animal (Fig. 3) is 

 found in the mountains of the interior, or in the hilly 

 country explored by me north and south of the equator. 

 It is found along the water-courses of limpid and clear 

 streams, where fish are abundant. It hides under rocks 

 along these streams, lying in wait for fish. It swims 

 through the water with a rapidity which astonished me ; 

 before the fish has time to move it is caught. On account 

 of the rapidity of its movements I have given it the specific 

 name of Velox. The animal returns to land with its prey 

 almost as rapidly as it started from its place of conceal- 



ment. The great motive power of the animal in the water 

 seems to be in its tail." 



So far as we have been able to read over this volume, we 

 have found that great pains have been taken to record all 

 the novel facts known about the animals here treated of. 

 We perceive an account of the nest-building power of 

 that most extraordinary Madagascar lemur, the Aye-Aye 

 {Cheiromys madagascarensis) and the strange instances of 

 mimicry about the bats, first noticed by Dr. DobsoD, is 

 to be found also noticed. 



An index to each volume would be a very desirable 

 addition. 



NITRIFICATION 



nPHE origin of salpetre is a subject which has vexed 

 ■■■ the minds of several generations of chemists. Nitrate 

 of potassium, or salpetre, is found in nature as a white 

 crust, appearing on certain rocks, old walls, and even 

 upon the surface of the soil ; from this mode of occur- 

 rence' the name "salpetre" is doubtless derived. The 

 largest natural source of salpetre is afforded by certain 

 soils in India. Soil having a white film of salt on the 

 surface is collected from the neighbourhood of house- 



drains and stables ; the soil is washed with water, and 

 the nitre crystallised from the solution. With this Indian 

 salpetre England has been, till quite recently, almost ex- 

 clusively supplied. The countries of Continental Europe, 

 not having access to so considerable a natural source of 

 nitre, have been obliged from early times to produce nitre 

 for themselves. At first the earthen floors of cottages 

 and stables were collected, washed, and nitrate of potas- 

 sium obtained by treatment with wood-ashes and crystal- 

 lisation ; but the inconvenience of collecting such mate- 

 rial, and its general poverty in nitre, soon led to attempts 



