1902.] JACOBSON IN THE ELEPHANT-SIIREW. 22o 



Ptxrker has shown that in the allied genera Petrodromus and 

 lihyncJiocyon there are a considerable number of Marsupial 

 chaiacters. In the Hedgehog the organ is formed on the common 

 Eutherian type, and I expected to find in Macroscelides indications 

 of marsupial affinity. When the organ was investigated, however, 

 it w-as seen to be quite different fi'ora that in any Eutherian 

 hithei'to examined, and to be typically Marsupial in almost eveiy 

 respect. 



Befoie entering upon compai'ative observations, it will be con- 

 venient fir.->t to desciibe the condition of parts in Macroscelides. 



If a section be made near the middle of the proboscis, it will be 

 seen (PL XXI. fig. 2) to be formed of a ring of caxtilage {a.n.), 

 enclosing the two nasal passages and sui-rounded by soft tissues — 

 muscles, tendons, and skin. The skeletal portion is made up of a 

 well-developed median nasal septum («..s.) and two alinasals (a.n.), 

 which sweep round fi-om the upper end of the septum and meet 

 each other inferioi'ly. From this lower point of union of the 

 iuinasals they pass upwards to meet the lower end of the septum. 

 From the inner side of each alinasal, near- the level of the base of 

 tlie septum, there passes inwards a small turbinal which is an 

 anterioi' continuation of the inferior nasal turbinal ; and from the 

 }3oint where the incurved end of each alinasal meets the base of 

 tlie septum there passes downwards and outwards a second 

 turbinal plate which may be refeii'ed to as the sejotal ti(,rhinal {s.t.). 

 With very little modification, this desciiption might refer to 

 any section of the proboscis. On approaching the anterior end 

 (Pi. XXI. fig. 1), however, the turbinals are found to be less 

 developed, the nasal septum slender and fused with the alinasals 

 infei'iorly, and the upper half of the alinasals to be separated 

 from the lower. Near the anterior na-al opening a transverse 

 section shows a pair of alinasals above, a pair of cai-tilages 

 on the nasal floor, and a pair of rather complicated lateral 

 cartilages which apparently form nasal valves. The anterior 

 nasal opening looks outwards and slightly downwards. 



In a traiisvei'se section near the root of the proboscis, the only 

 notewoi'thy differences from the more anterior sections are that 

 the base oi the septum is considerably larger, while the lower 

 halves of the alinasals are not only separate fi'om each other-, 

 but are distinct from the alinasals above — forming nasal-floor 

 cjxrtilages. 



When the plane of the premaxilla is reached (PI. XXI. fig. 3), 

 the outer and lower part of the nasal-floor cartilage becomes lost, 

 only the part situated immediately below the base of the septum 

 and which forms the septal turbinal remaining. 



A few sections in front of the plane where the palatine process 

 is given off from the premaxilla, the premaxilla {pmx.) sends 

 upwards a narrow plate as a support to the inner side of each of 

 the two cartilages which lie at the base of the septum. These 

 plates form the a,nterior ends of the palatine processes (75.^?.). 

 About this same plane tlie small cartilaginous plates, which in the 



