May^I, 1893.] 



KNOWLEDGE 



83 



sub-division of the Miiridiv) have also taken to a subter- 

 ranean burrowing life, * with the assumption of a mole-hke 

 bodily form. These may be termed mole-voles, and range 

 from Russia to central and northern Asia, where they are 

 represented by the two genera Ellahius and Sijihneus. They 

 all have mole-like heads and bodies, short limbs and tails, 

 rudimental external ears, very minute eyes, and powerful 

 fore-paws. In the Russian mole-vole (Elluhiio:) and the 

 allied Quetta mole from Afghanistan the claws of the front 

 paws are short ; but, as shown in our figure, they become 

 greatly elongated in the members of the genus Siphnem. 

 All of them agree with the ordinary voles in the peculiar 

 structure of their molar teeth, which consist of a number of 

 triangular prisms placed edge to edge. All these animals 

 are described as driving subterranean tunnels and throwing 

 out at intervals heaps of earth precisely after the fashion 

 of the common mole. 



The foregoing are the only rodents which have assumed 

 a more or less distinctly marked mole-like external form 

 while retaining all the characteristic structural features of 

 the order to which they belong. There are, however, two 

 other members of the same great order which, while having 

 acquired mole-like habits, have not assumed a distinctly 

 mole-like form. One of these is the tuco-tuco (Ctenomys) 

 of South America, belonging to the same great family as 

 the capybara and the coypu. This animal is rather 

 smaller than a rat, with a relatively shorter tail, pale grey 

 fur, and red incisor teeth. Its general form is also not 

 unlike that of a rat, the limbs being of fair length, and the 

 front paws not markedly enlarged, while the eyes are of 

 considerable size. The external conchs of the ears have, 

 however, been greatly diminished in size. The tuco-tuco 

 derives its name from its voice, which resounds day and 

 night from its subterranean dwellings, and is compared by 

 Mr. W. H. Hudson to the blows of a hammer on an anvil. 

 It frequents loose and sandy soil, although occasionally 

 found in moist heavy mould, through which it pierces its 

 way as readily as the mole. Darwin, who states that the 

 tuco-tuco is even more subterranean in its habits than the 

 mole, was told by the Spaniards that blind examples were 

 often captured. This, however, is not the experience of Mr. 

 Hudson, who lays stress on the relatively large size of the 

 creature's eyes. From the soft nature of the soil in which 

 it tunnels, it is not difficult to understand why it has 

 been unnecessary for the tuco-tuco to assume a mole-like 

 bodily form ; but the reason for the retention of fully- 

 developed eyes— which we should have thought exceedingly 

 prone to injury — is hard indeed to divine. 



The other rodents with mole-like habits are two tiny 

 little creatures from the sandy districts of Somaliland, 

 locally known by the name of farumfer, and scientifically 

 as Heterocephalus. They are about the size of a mouse, 

 with large hands, moderately long tails, long powerful 

 fore-feet, no external ear-conchs, minute eyes, and the 

 whole skin naked, save for a few sparse bristly hairs. 

 About as ugly a creature as can well be conceived, the 

 farumfer, if clothed with a thick coat of fur, would be not 

 very unlike a rather long-tailed, long-hmbed, and narrow- 

 handed mole. For tunnelling beneath the hot sand of the 

 Somali desert the naked skin of the farumfer is most 

 admirably adapted ; and as the creature is alhed to the 

 South African Geonjchus, it may be regarded as the member 

 of this group most specially adapted for a subterranean 

 existence. Mr. E. L. Phillips, who was the first to observe 

 these curious rodents in the UvLag state, writes that they 

 threw up in certain districts groups of elevations in the 



sand which may be compared to miniature volcanic craters. 

 When the animals are at work the loose sand from their 

 tunnels is brought to the bottom of the crater and sent 

 with considerable force iato the air with a succession of 

 rapid jerks, the rodents themselves remaining concealed in 

 the shelter of their burrows, from which they appear never 

 to venture forth. 



As we have had occasion to notice in a previous article, 

 the extensive assemblage of pouched or marsupial mammals 

 contains groups corresponding to several of those of the 

 placental or higher mammals. Thus, for instance, the 

 kangaroos in Austraha play the same role as the deer and 

 ruminants in other parts of the world, while the Tasmanian 

 wolf takes the place of the ordinary wolf, the wombats 

 act the part of the marmots, the phalangers of squirrels, 

 and the bandicoots of the civets and weasels. Till 

 quite recently it was thought that the place of the moles 

 (whether insectivorous or rodent) was unoccupied in the 

 Antipodes, and that no marsupial had adapted itself to a 

 tunnelling subterranean existence. Within the last few 

 years it has, however, been discovered that the sandy 

 deserts of south central Australia are inhabited by a 

 small burrowing creature belonging to the pouched group, 

 which has been fitly termed the marsupial mole {Xotorijctes) ; 



* It should be mentioued that hj the term "burrowing" is here 

 meant the construction of tunnels, and not a mere dwelling hole. 



Fig. .3. — Undiu- surface of tin- Marsupial Mole, two-thirds 

 natural size. (After Stirling.) 



and it is not a little remarkable that in general appearance 

 this tiny animal is even more mole-like than are some of 

 the above-mentioned burrowing rodents, thus showing how 

 all powerful is adaptation to environment, and of how 

 little import is internal structure in modifying the external 

 form of an animal. The general mole-like appearance of 

 the Australian burrower will be apparent from the accom- 

 panying figure ; the most striking mole-like features being 

 the elongated and depressed body passing imperceptibly 

 into the head, the absence of external ear-conchs, the 

 rudimentary pin-like eyes, the small tail, and the short 

 limbs, of which the front pair are armed with claws 

 of great power. The marsupial mole stands alone, how- 

 ever, in having the front of the muzzle protected by a 

 leathery shield ; while its short and blunt tail is also 

 covered with a peculiar naked leathery skin. In the fore 

 limbs the structure of the feet recalls the golden moles 

 rather than the true moles, the third and fourth toes being 

 greatly enlarged at the expense of the others, and furnished 

 with huge triangular claws of enormous digging power. 

 In its pale, sandy-coloured hair, with a more or less golden 

 tinge, the marsupial mole departs widely from our sable 

 European friend ; but it must be remembered that the 

 difference in this respect is really not so great as it at first 

 sight appears, seeing that cream-coloured varieties of the 

 common mole are far from rare. In the Australian form 

 the pale coloration is doubtless adapted to harmonize with 

 the natural surroundings of its native desert, since it has 

 been ascertained that the creature makes its appearance 

 from time to time above ground. That the resemblance 

 of the marsupial to the golden mole in the structure of 



