591 



OX THE COMPARATIVE ANATOMY OF THE ORGAN 

 OF JxVCOBSON IN MARSUPIALS. 



By R. Broom, M.D., B.8c. 



(Plates xli.-xlviii.) 



Although the researches of Gratiolet, Balogh, Klein, and others 

 had made us faniiliar with the structure and relations of Jacob- 

 son's organ in a number of the principal types of higher Mammals, 

 until ^•ery recent years no examination appears to have been made 

 of the organ in any of the Marsupials. 



In 1891, Symington jjubhshed a paper "On the Organ of 

 Jacobson in the Kangaroo and Rock Wallaby," in which he 

 points out the main features of the organ and its relations, and 

 gives figures of transverse sections at the opening of the organ 

 and also at its most developed part.. He concludes that the 

 Marsupial organ agrees very closely with the Eutherian type, and 

 differs markedly from that found in the Protothei'ian Ornitho- 

 rhynchus. It is unfortunate that when his paper was written only 

 the aberrant Platypus type had been carefully studied, for had 

 he compared the Marsupial organ with the simpler Monotreme 

 type as found in Echidna, his conclusion would probably have 

 been different. 



In 1893, Rose, apparently ignorant of Symington's work, 

 published a very short paper on the organ in the Wombat and 

 Opossum. He gives two good figures of the organ in the young 

 Wombat, but makes no remarks on the peculiai'ities of the organ 

 or its relations. 



The only other papers, as far as I am aware, in which the 

 Marsupial arrangement is touched on are, Symington's recent 

 paper "On the Hortiology of the Dumb-bell-shaped Bone in 



