BY J. T. WILSON. 145 



Again, in Erinaceus europaeus, the anterior vomers are shown 

 in ri. XIX. figs. 1, 3, 7 and 8 (v'.), where tlieir intimate relation to 

 the " recurrent cartilages" or cartilaginous capsules of Jacobson's 

 organs is most striking. Cf. also the transverse sections, figs. 4 

 and 5 of PL xviii. 



In reference to the anatomy of the region under notice inTatusia 

 hybrida, Parker has made the following observation (loc. cit. 

 p. 18): — "The cartilages protecting 'Jacobson's organs' are no 

 longer tubular, but form half a tube, open externally, the organ 

 lying in the outer hollow. But the cartilages themselves have an 

 osseous countei'part protecting them on the inner side and having 

 their shape and direction ; these are the ' antei'ior paired vomers,' 

 bones well known for their large development in the Ophidia and 

 Lacertilia ; they do not represent a divided ' vomer,' proper, 

 which in nearly all Mammalia is well developed also." This 

 description could almost stand for one of the actual conditions in 

 the adult Ornithorhynchus, the paired "anterior vomers" being 

 of course fused mesially. 



Thus, if Parker's splendid work could be taken as final, there 

 could be little hesitation in identifying the dumb-bell bone as the 

 horaologue of the "anterior vomers" described and figured by him 

 ill so many edentate and insectivorous types of Mammalia, as well 

 as in the Ophidia and Lacertilia. 



The figures illustrative of Herzfeld's paper on the organ of 

 Jacobson (13) are also worthy of study in this relation, but in the 

 text this author states that he has simply adopted from Balogh (14) 

 the identification of the bone lying mesially to the incisive foramen 

 as palatine process of premaxilla. Some of the figures, however, 

 show a dorsal extension of this osseous region which is at least 

 highly suggestive of a true vomerine character. 



Professor Howes, however, has stated (loc. cit.) the opinion that 

 Parker's views respecting the various elements of the vomerine 

 series in the Mammalia are not entirely devoid of uncertainty, and 

 in particular he holds that Parker has " shown that he was unable 

 to draw a sharp distinction between the palatine processes of the 

 premaxillie and his anterior paired or lateral vomers." Never- 

 10 



