lvon] the hares and their allies 36' 



ing the condition found in Roiucrolagus. These processes are char- 

 acteristic of the genus Liiiuiolagtis. 



4. Small rabbits having the lumbar transverse process slightly 

 more concave anteriorly than in the other rabbits. Each process 

 is marked by a prominent longitudinal ridge. But for this pro- 

 nounced ridge the lumbar transverse process resembles that found 

 in the genus Sylvilagus. While this ridge is found to a greater or 

 less extent in the other groups of the Leporidse, yet it is never so 

 narrow nor so sharply marked off from the rest of the process. 

 The transverse processes of this type are peculiar to the genus 

 Brachylagus. 



5. Small rabbits with the lumbar transverse processes short, the 

 longest equaling the length of the centrum to which it is attached. 

 The process of the first lumbar vertebra is very short and almost 

 rudimentary. All the processes are wide and have triangular out- 

 lines in general. The base is broad, coming from the whole side 

 of the centrum, and the angle between the main axis of the process 

 and the side of the centrum is completely filled with thin bone. It 

 is an exaggeration of the condition found in Liuinolagits. Even the 

 transverse process of the last lumbar vertebra, which is usually 

 slender in other rabbits, is here very broad, but not so broad as the 

 transverse processes on the other lumbar vertebrae. Transverse 

 processes of this type are characteristic of the genus Roiucrolagus. 



6. JMedium-sized rabbits with lumbar transverse processes of 

 medium length, the longest equaling the length of the centrum to 

 which it is attached. The process is not so much expanded at the 

 free extremity as in the case of the above groups. It is wide how- 

 ever at the base, where it comes from the whole side of the centrum, 

 resembling in this respect Limnolagus, but the posterior border of 

 the transverse process is not so strongly concave as in that genus, 

 and the process itself is more slender. Transverse processes of this 

 type are found in the genus Pronolagus. 



The other variations in the lumbar vertebrae are of less importance 

 and not so well defined as are the variations of the transverse 

 processes. 



The spinous processes and metapophyses are always well de- 

 veloped. In the anterior part of the lumbar region the spinous 

 processes are usually a little longer than the metapophyses on the 

 same vertebra and they are always longer in the posterior region. 

 The spinous process is of variable shape and there are marked 

 differences in individuals of the same spscies. This process is, 

 in general, bluntly triangular, sloping obliquely anteriorly, the basal 



