348 LIEUT. R. BROOM OX THE 



The Organ of Jacohson in Talpa. (PL III. figs. 1-7.) 



Proif. Kitchen Parker in 1885 figured a number of sections 

 (ffitf Ifche nose of the young of Talpa. While these show the general 

 structure and relations of tlie nasal cartilages, they do not clearly 

 shew the structures in the neighbourhood of the naso-palatine 

 caaaafl. 



Though the young mole which I have examined has the 

 cartilage in the anterior part of Jacobson's duct imperfectly 

 ch®ndrified, the yovmg animal reveals the structures more clearly 

 than does the adult in which the bones are so highly ossified and 

 anckylosed. 



In the anterior part of the nose there is little worthy of special 

 note. One unusual feature is the thinning-out and perforation 

 of the icairtilage of the septum a short distance behind the 

 plane of the nostril. As the sections of the snout have been cut 

 of uniform thickness, the number of the section figured or 

 described Avill indicate the situation of the various features. 

 This anterior pei'foration of the septal cartilage is between 

 sections 19 and 22. 



Immediately behind the perforation the upper part of the 

 septum begins to thicken. Fig. 1 represents section 36. The 

 thick alinasal cartilnge is seen curving round and united with 

 the thick outer part of the anterior nasal-floor cartilage. Outside 

 the cartilage is seen the lacrimal duct, and inside, the duct of the 

 nasal gland. 



From the plane of this last section to section 76, the nasal 

 cavity is completely surrounded by cartilage. The upper part of 

 the septal cartilage becomes gradually more thickened. Fi'om 

 section 60 a median groove passes upwards into the lower part of 

 the septum gradually dividing the cartilage into two. Fig. 2 

 represents section 74. Here the lower parts of the median 

 cartilage are almost separated from the upper septal cartilage to 

 form the recurrent cartilages. The anterior part of the pre- 

 maxilla is seen ; the bones of the two sides are not clearly 

 separable. 



Three or four sections beyond that shown in fig. 2 the 

 recurrent cai-tilage is free from the base of the septum and also 

 from the lower pai-t of the alinasal. A similar condition occui's 

 for aboiit twenty sections. In section 96 is seen the anterior 

 part of the naso- palatine canal. 



Fig. 4 represents the condition at section 100. On the left 

 side the duct of Jacobson's organ is seen opening into the canal. 

 On the light side, the duct of the organ is seen lying above and 

 slightly to the outer side of the canal. The anterior part of 

 Jacobson's cartilage is seen lying above the duct. The recurrent 

 cartilage is well developed. 



Fig. 3 represents section 103. The duct of Jacobson's organ 

 is seen immediately above the naso-palatine duct. 



In fig. 5, which represents section 110, the naso-palatine duct 



