June 1, 1898.] 



KNOWLEDGE 



1?.9 



countries, the lion and the leopard being found alike in Africa 

 and India ; but auch do not detract from the peculiarity of 

 the African fauna as a whole. And here it may be mentioned 

 that a large proportion of the types now peculiar to 

 the Dark Continent appear to have come from India or 

 some adjacent country, fossil remains of baboons, giraffes, 

 hippopotami, ostriches, antelopes of an African type, and 

 not improbably zebras, having been discovered in the 

 Tertiary deposits of India. 



But if the animals of Africa as a whole stand out in 

 marked contrast to those of the rest of the world, much 

 more is this the case when those characteristic of certain 

 districts of that huge continent are alone taken into 

 consideration. And most especially is this so with the 

 inhabitants of the great tropical forest districts extending 

 from the west coast far into the interior of the continent — 

 reaching, in fact, the watershed between the basins of the 

 Congo and the Nile in thu neighbourhood of Wadelai. 

 Since a large number of the peculiar animals of this district 

 are more or less exclusively confined to the west coast, 

 extending from Sierra Leone to the Congo, the area is 

 appropriately termed the West African sub-region. It is 

 here alone that we find the gorilla and the chimpanzee, 

 the former being restricted to the neighbourhood of the 

 coast, whereas the latter ranges far into the heart of the 

 continent. And this district is likewise the exclusive 

 home of the pretty little mangabys, or monkeys with 

 white eyelids (Cercdcelnni). The galagos, which are near 

 relatives of some of the lemurs of Madagascar, extend 

 throughout the forest region ; but the even more curious 

 pottos, or thumbless lemurs, are confined to the west coast. 

 Huge and forbidding fox-bats, some of them with remark- 

 able tufts of long white hairs on the shoulders, are likewise 

 restricted to this portion of the tract, as is the insecti- 

 vorous otter, or Potumoijale, first discovered during the 

 travels of Du Chaillu. The equatorial forest tract is also 

 the sole habitat of the African tiyiug squirrels, distinguished 

 from the very different flying squirrels of Asia by the 

 presence of a number of scales on the under surface of the 

 tail. Most of these belong to the genus Anomnluni.s, but 

 the smallest of all forms a genus {[diurus) by itself, and 

 will be familiar to readers of this journal by a life-sized 

 portrait published some years ago. Dormice of peculiar 

 types and tree mice are also very characteristic of this 

 tract. But far more generally interesting are the pigmy 

 hippopotamus of Liberia and the water chevrotain (Dorca- 

 tlieriuw) of the west coast, an ally of the true chevrotains 

 of India and the Malay countries. So far, indeed, as the 

 equatorial forest tract fauna has any representative in 

 other parts of the world, it is to the Malay peninsula 

 and islands that the resemblance is closest. It is there 

 alone that the other large manlike ape — the orang — 

 dwells ; and there is a group of brush-tailed porcupines 

 common to these two districts, and unknown elsewhere 

 throughout the wide world. Both faunas, however, in all 

 probability trace their descent from the animals inhabiting 

 Europe during the Pliocene and Miocene epochs, among 

 which was an extinct species of water chevrotain. 



The other great sub-regions include the open grazing 

 grounds and mountains of South and East Africa, the fauna 

 of which is quite different from that of the equatorial forest 

 tract. Minor divisions may also be recognized in this area, 

 the Cape having many animals not found further north. 

 Among the latter are the so-called white rhinoceros, the 

 pretty little meerkat(.SK?uY(f«), the long-eared fox ((Jtocyon), 

 and the Cape sand mole (Butliyergux), which, by, the way, 

 has nothing to do with the true moles, being a member of 

 the rodent order. This tract as a whole may be termed the 

 east central sub-region ; and to it belong the great hosts 



of antelopes, the zebras, and the aard-wolf and hunting 

 dog. Very characteristic of the southern and eastern parts 

 of this tract are the beautiful golden moles (C/u-yscldorh), 

 unique among mammals for the lovely play of iridescent 

 colours on the fur, and which have comparatively nothing 

 in common with the moles of Europe and Asia. To 

 the northward, in Abyssinia, this tract is the home of 

 another very remarkable animal, the great gelada baboon 

 {TheropithccHs), easily recognized by the lionhke mantle 

 of long hair on the fore quarters, whose nearest relatives 

 are the ordinary baboons of Africa. 



Whether Somaliland should be included in this area, or 

 should have a division to itself, may admit of argument ; 

 but at any rate it has many peculiar animals, among 

 which are a number of antelopes, some of which have but 

 recently been made known to science. 



Lastly we have the Saharan sub-region, which contains a 

 comparatively limited fauna, passing by almost insensible 

 degrees into that of Northern Africa. 



In some respects, especially in its galagos, the fauna 

 of Africa presents a certain resemblance to that of 

 Madagascar ; but the connection between that island and 

 the mainland was evidently very remote, and must have 

 taken place before the great incursion of antelopes, zebras, 

 rhinoceroses, monkeys, elephants, etc., from the north, as 

 none of these are found in the island. Madagascar, there- 

 fore, is best regarded as forming a zoological province by 

 itself. 



Within the limits of a single article it is manifestly 

 impossible to give aaything like an adequate sketch of the 

 fauna of such an extensive area, but such points as have 

 been noticed serve to sho'.v in some faint degree its rich- 

 ness in peculiar forms of animal life. 



THE VINEGAR FLY AND THE VINEGAR MITE. 



By C. AiNswoRTH Mitchell, b.a., f.i.c. 



THE vinegar eel, of which a description appeared in 

 a recent number of Knowledc-e (page 53), is not 

 the only creature with a marked partiality for 

 vinegar, for two other animals have become so 

 associated with its manufacture that they are 

 known as the vinegar fly and the vinegar mite. 



The vinegar fly [DrosophUa funebris) is of very common 

 occurrence, and may be found in any vinegar works during 

 the hotter months of the year. It is about a tenth of an 

 inch in length, and is characterized by large red eyes, red 

 thorax, and red legs. The abdomen is black with yellow 

 stripes, and the wings are somewhat longer than the body. 

 According to Brannt the larva is white, has twelve seg- 

 ments to its body, and four wart-like structures on its 

 back, two of these being yellow. After eight days it is 

 transformed into a yellow chrysalis. 



Vinegar makers are not in the habit of paying much 

 attention to the presence of the vinegar fly, since, as far as 

 is known, it does not in any way aflect the manufacture ; 

 and it is readily prevented from becoming a nuisance by 

 keeping the works thoroughly clean and not allowing any 

 spilt vinegar to lie about on the ground. 



The vinegar mite, unlike the fly, must be regarded as a 

 distinct enemy to the acetic bacteria, though not, perhaps, 

 to the same extent as the vinegar eel. When once it has 

 obtained a footing within an acetifier it multiplies with 

 amazing rapidity, interferes with the oxidation process, 

 and is not easily exterminated. Dr. Bersch describes the 

 state of an Italian factory about which he was consulted 

 in 188L Every drop of vinegar produced contained one 

 or more of these mites, which were present in myriads 



