1902.] JACOBSOX IN THE ELEPHAXT-SHREW. 227 



Whtile almost all Marsupials exhibit these features, no higher 

 mammal hitherto examined agrees with the Marsupials in more 

 than three of these characters. The peculiar condition of Jacob- 

 son's cartilage, whereby a cartilaginous bar is present along the 

 outer wall of the anterior part of the organ, and which I regard 

 as a remnant of the tiu'binal of Jacobson's organ retained in the 

 IVEonotremes, is among the Euthei-ia only met with in the Eden- 

 tata {Dasypus), and in a rudimentary condition in some Rodents. 

 Only the Edentates again agree with the Marsupials in the 

 absence of a cartilaginous suppoi't to the naso-palatine canal. 

 The presence of a cartilage in the papilla, though occiu'ring in 

 most Marsupials, has hitherto only been observed among higher 

 mammals in the little Bat Jliniopterus, and possibly as a rudiment 

 in Cavia. 



Fi-om the fact that Jlcwroscelides agrees with the Marsupials in 

 every detail of the anatomy of this region, we are forced to the 

 conclusion that it is a very near relative of the Marsupials, and 

 has probably very little affinity with the more typical Insectivores, 

 That the marsupial characters are not confined to the nose we 

 know from Parker's work. In the tympanic region and in the 

 remarkable condition of the orbito- sphenoid the marsupial affinities 

 are quite as remarkable. 



It is further interesting that, while Macroscelkles in the anatomy 

 of its anterior nasal region agxees more closely with Perameles 

 than with other Marsupials, Perameles in one or two respects 

 agi'ees more closely with Afacroscelides than with most of the 

 typical IMarsupials. The striking sunilarity of structure is shown 

 in the dra^\•ing (Plate XXI.), wheie a section of the antei'ior pait 

 of Jacobson's organ in Perameles is shown (PI. XXI. fig. 10) for 

 comparison with the section of JIacroscelides (fig. 8). 



It may be noted that JIacroscelides has a discoidal deciduate 

 placenta, and that the young aie born in a well-developed con- 

 dition. 



EXPLANATION OF PLATE XXL 



Meferoices. — a.J.c. anterior portion of Jacobson's cartilage ; a.J.o., anterior por- 

 tion of Jacobson's organ ; a.n., alinasal ; a.p.p., anterior spur from palatine process ; 

 ^., glands; /.c, small isolated cartilage — possibly a rudimentary St enson's cartilage 

 (not indicated in the adult) ; i.f., inferior turbiual : J.c, Jacobson's cartilage j J^., 

 Jacobson's organ ; l.d., lachr\Tnal duct; n.g., nasal gland; m.x., maxilla; n.p.c, 

 naso-jialatine canal ; w.s., nasal septum ; o.h.J.c, outer bar of Jacobson's cartilarge ; 

 p.c, cartilage of papilla ; pmx., premaxilla ; p.p., its palatine process ; s.t., septal 

 turbinal. 



Eigs. 1, 2, 3, 4. Transvei'se section of snout of fojtal JIacroscelides proboscideit-s. 



X 24. 

 Figs. 5, 6, 7. Transverse section of the same region of naso-palatine canal. X 40. 

 Figs. 8, 9. Transverse section of Jacobson's organ in adult Macroscelides. X 18. 

 Fig. 10. Transverse section of anterior end of Jacobson's organ in Ferameles nasuta 

 (young). X 17. 



Addendum. {JIarch 1902). — While writing this paper I had 

 taken for granted that the cranial characters desciibed by Pai-ker 

 in Rhynchocyon and Petrodromus would be common to the other 



