342 SMITHSONIAN MISCELLANEOUS COLLECTIONS [vOL. 45 



length that it has in Lcpiis. In SylvUagns (Microlagiis) cincrasccns 

 the bony palate is short, but in S. (M.) bachmani it is distinctly 

 longer. In Liuinolagiis and Oryctolagus the bony palate lengthens, 

 relatively speaking ; the horizontal plate of the palate bone is better 

 developed and enters into the formation of the bony palate to a 

 slightly greater extent than in the case of the preceding genera, but 

 to a less extent than it does in Roincrolagus. The portion of the 

 palate bone that borders the maxilla caudad of the posterior edge 

 of the bony palate is better developed in Liinnolagus and Oryctolagus 

 than it is in Lcpus, SyhvUagus, or Brachylagits, and thus forms part 

 of the roof of the mouth along the posterior dental alveoli. This 

 development of the palate bone just internal to the dental alveoli 

 is better developed in Oryctolagus than in Limnologus, and it is 

 still further developed in the genera Rouicrolagus and Pronolagiis. 

 The last has the longest and narrowest bony palate of any of the 

 Leporidffi at hand, though Rouicrolagus has one nearly as long 

 relatively. The horizontal plates of the palate bones in these two 

 genera form about the posterior half of the bony palate. Pcnta- 

 lagus and Ncsolagus have long palates resembling those of Rouicro- 

 lagus and Pronolagiis, but the horizontal plates of the true palate 

 bones form only the posterior fifth or fourth of the bony palate. 

 The palate of Caprolagiis is apparently similar, but the horizontal 

 plates of the palate bones form its posterior third. 



In most of the Leporidse the posterior palatine foramina are of 

 moderate size and are located between the palatine plate of the maxilla 

 and the horizontal plate of the palate bone, at the anterior outer 

 angles of the horizontal plate. In Rouicrolagus, however, the 

 posterior palatine foramina are relatively very large and in the 

 usual position. In Pronolagiis the posterior palatine foramina are 

 very small, and are scarcely visible except for two grooves leading 

 from them. They are situated not at the anterior outer angles of 

 the horizontal plate of the palate bones, but are found near the 

 median line, toward the anterior internal angles of the horizontal 

 plates of the palate bones. 



Variations about the posterior narcs or choance, and zvidth of the 

 incisive foramina.— Certain variations are found in the degree of 

 approximation of the vertical plates of the palate bones, the height 

 of the pharyngeal vault, and the width of the incisive foramina, and 

 when compared with the length of the bony palate measured half-way 

 between the median line and the dental alveoli, there are found 

 ratios which are seen to be fairl}' constant for the diiTerent groups 

 of the Leporid^e. 



