ON THE ORGAN OF JACOBSON IN THE INSECTIVOUA. 347 



25. On the Organ o£ Jacobson and its Relations in the 

 " Insectivora." — Part II. Talpa, Centetes, and Chri/so- 

 clilons. By Lieut. R. Bkoom, M.D., D.Sc, C.M.Z.S., 

 R.A.M.C. 



[Received April 27, 1915 : Read May 11, 1915.] 

 (Plates III. & IV.*) 



Index. 

 Structure : Page 



Ta/jpa, Organ of Jacobson 348 



Centetes, Organ of Jacobson ■. 349 



Chri/sochloris, Organ of Jacobson 351 



When six weeks ago I undertook the examination of the 

 Organ of Jacobson and its relations in Tivpaia and Gymnura, 

 I was merely anxious to see if Tupcda agreed with Macroscelides, 

 and Gymnura with Erinac&us, as an agreement would give 

 further evidence of the value of this region of the skull as a basis 

 of classification, and also strongly support the removal of Macro- 

 scelides, Ihvpaia, and allied genera from the Insectivora and the 

 placingof them in a distinct order — Menotyphla. As I have shown 

 in Part I. of this paper, Iktpaia agrees sufficiently closely with 

 Macroscelides — both having the Polyprotodont Marsupial type 

 of organ — to admit of their being placed in the same order ; 

 while Gymnura was shown to have the higher Eutherian tyjDe of 

 organ met with in Erinaceus, Felis, Ovis, and all higher forms in 

 which the organ is retained. 



When I had finished the study of these two types, I thought 

 it would be worth while to look at the condition in the aberrant 

 African Golden Mole, Chrysochloris ; and as Prof. J. P. Hill had 

 two very fine specimens which I had given him some years ago — 

 a newly-born ChrysoGhlo7-is kottentota and a slightly older Chryso- 

 chloris asiatica — he very kindly had the heads sectioned so that I 

 might examine them. The results were so interesting that it 

 was necessary to go further with the research. Through the 

 kindness of Mr. Oldfield Thomas, of the British Museum, I 

 obtained the snout of a Centetes which I have examined, and also 

 adult specimens of the common mole and shrew. Prof. Hill 

 very kindly had sectioned for me the head of a very young 

 mole. To these gentlemen, and also to Prof. Hill's laboratory 

 assistant, Mr. F. Pittock, I am deeply indebted. 



* For explanation of the Plates see p. 354. 



Proc. Zool. Soc— 1915, No. XXY, 25 



