EEINACEUS iETHIOPICUS. 
16 :^ 
species does not occur in Egypt properly so-called. It was in all likelihood found by 
him in the same region in which he procured the last-mentioned specimen. Although 
it bears the name of E. libycus, it is perfectly apparent that it is not that species, as it 
corresponds to the present one. 
Heuglin’s two specimens are of considerable interest, as they suggest that the species' 
found in the Tunisian and Algerian Sahara, known as E. deserti, Loche, is only a local 
race of the eastern Sudan form. The latter departs in certain particulars from the 
Tunisian hedgehog, as its ears are larger and the longitudinal ridges on its spines less 
numerous; but in this latter respect there is no sharp line of demarcation between 
the two, as the ridges in the Sudan specimens number 18 to 22 and in those from 
Tunisia 22 to 24. 
The skulls of Tunisian and Eastern Sudan hedgehogs are identical in their general 
features, but the teeth of the latter are slightly smaller. 
This hedgehog is of special interest when it is studied in connection with the forms 
already indicated of E. dorsalis^ E. micropus, and E. pictus. The type of skull is tlie 
same in all—that is, the pterygoids are dilated, and the cavity enters into the formation 
of the auditory chamber in the dried skull; but what the exact relationship of this 
extended bullate cavity is to the rest of the true auditory apparatus has yet to be definitely 
ascertained by dissections of fresh skulls. As no other existing mammal, that 1 am 
aware of, has its pterygoids dilated to assist in the perfection of the sense of hearing, 
it would appear to be a legitimate inference that E. cethiopicus is a more highly 
specialized and more recent form than E. europceus, Linn. 
All the known extinct hedgehogs have pterygoids like the last-mentioned species^, 
and until fossil remains of hedgehogs with the type of auditory apparatus found in 
E. cethiopicus are met with of older geological date than the extinct representatives 
of E. europceus, it is logical to assign the E. cethiopicus type to a more recent origin. 
In E. macracanthus and E. jerdoni the pterygoids do not present the same degree of 
hollowing out as in E. micropus, while at the same time the skulls unquestionably 
belong to the same type as that of the latter species ; and consequently in the structure 
of the pterygoids they serve to connect the extreme modification of these bones 
presented by E. cethiopicus, E. dorsalis, E. micropus, and E. pictus with that distinctive 
of E. europceus. 
The occurrence in Southern and North-western India of hedgehogs closely allied in 
skull-characters to E. cethiopicus of Africa and its near ally of Arabia, E. dorsalis, is of 
extreme interest and very suggestive of the close relationship which is now recognized 
to have existed at no very remote period between the fauna of the Africo-Arabian region 
and that of Southern India. 
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