388 ROBERT J. TERRY 



canal. In Ornithorhynchus and Echidna this cartilage expands 

 at its caudal end and unites with its fellow across the midline 

 to form a broad plate beneath the organ of Jacobson and its 

 cartilaginous capsule. The conditions in the MarsupiaUa were 

 traceable to those of the monotreme type. In Lepus, as repre- 

 senting the rodents, Broom found an independent cartilage sup- 

 porting the outer side of the nasopalatine canal, which was ho- 

 mologized with the outer nasal floor cartilage of the Monotremes, 

 and was regarded as a much modified form, compared with the 

 simple higher eutherian type. Voit has also described, under the 

 name cartilago nasopalatina, the supporting cartilage for the naso- 

 palatine duct in the rabbit, and, with Gaupp, compares it with 

 the processus palatinus (outer nasal floor cartilage of Broom) of 

 Echidna. 



This comparison is founded by Voit mainly on the fact that in 

 certain mammals (horse, pig and sheep) the processus palatinus 

 (cartilago basalis laterahs as described by Spurgat, '96) is united 

 with the lamina transversalis anterior (processus septi cartilaginei 

 lateralis ventrahs) in the same relationship as is the case with the 

 processus palatinus of Echidna; and fiuther, that in at least one 

 form, Vesperugo noctula, described by Grosser ('02) the 'carti- 

 lagines posteriores laterales' (cartilagines nasopalatinae of Voit) 

 are considerably broadened posteriorly and fused across the 

 median line, as is true for the palatal processes of Echidna. 



Two conditions, presented by the cat, seem to indicate that the 

 significance of the nasopalatine cartilage and the processus pos- 

 terior laterahs of the lamina transversahs, is not fully brought 

 out by the above comparisons. These conditions are (a) the 

 presence, at the same time, of two separate cartilages, one in re- 

 lation to the nasopalatine duct (nasopalatine cartilage) the other 

 in the floor of the nose next to the entrance of the nasopalatine 

 duct (posterior lateral process of the transverse lamina) ; and (b) 

 the independent origin of the former. Furthermore, in regard to 

 the first condition, it seems evident, from Grosser's description 

 of Vesperugo, that both paired nasopalatine cartilages (cartilago 

 ductus incisivi) and posterior lateral cartilages are present and 

 separate, the one pair from the other. 



