186 MR. F. G. PARSONS ON THE (Jan. 14, 
while noticing that in no other respect does it approach. the 
Hystricomorpha ; consequently I think that the study of the 
muscles bears out the suggestion of Winge’ that Rhizomys is 
distinct from the Bathyergine, and that it should be placed 
among the Muride, which it resembles in the only common point 
which this family has—the decussation of the rectus. 
Winge* also suggests that Bathyergus is closely allied to the 
Hystricide. The following points in its myology show a diver- 
gence from the myomorphine and an approach to the hystrico- 
morphine arrangement :— 
1. The scalenus anticus is present and rises from the basi- 
occipital. 
2. The scapulo-clavicularis is present, as in all Hystricomorpha, 
while in no myomorphine rodent was it found. 
These two points alone would not of course justify one in 
separating the Bathyergine from the Myomorpha, but they show 
an approach to the hystricomorphine type which is suggestive. 
The Position of the Dipodide. 
A review of the muscles of Rodents would be incomplete without 
considering whether they lend any assistance towards determining 
the vexed question of the position of the Jerboas. In my former 
contribution I described their muscles with those of the Hystri- 
comorpha. Now that the muscles of the Myomorpha have been 
worked out, a comparison can be made between them. 
In the following points the Dipodide resemble the Hystrico- 
morpha :— 
1. The large size of the anterior deep part of the masseter 
passing through the infraorbital foramen. 
2. The presence of a scalenus anticus rising from the basi- 
occipital. 
3. The presence of only one head of the biceps cubiti. 
4. The non-decussation of the rectus abdominis at its origin 
with the muscle of the opposite side. 
5. The union of the tendons of the flexor tibialis and fibularis 
in the sole. 
The first point is only one of degree since the Myomorpha show 
a small piece of the masseter passing through the infraorbital 
foramen. 
The second has been found in Myowus among the Myomorpha, 
as well as in Bathyergus and Georychus, whose position is not 
quite certain. 
The third point is certainly in favour of hystricomorphine 
tendencies, as I have not yet found any myomorphine rodent 
without two heads to the biceps cubiti. 
The fourth point, the decussation of the rectus, is not always 
found in the Myomorpha, while it sometimes occurs, as in the 
pene among the Hystricomorpha. 
* E Museo Lundii,-1888, p. 109, 
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