ia 
1896.] MYOLOGY OF RODENTS. 189 
11. The gracilis is usually double in the Myomorpha, single in 
the Sciuromorpha. 
12. The accessorius is usually absent in the Myomorpha, always 
present in the Sciuromorpha. 
With a view to comparing the myology of the Lagomorpha with 
the other suborders, I dissected the muscles of a Hare and a Rabbit, 
but have refrained from enlarging this paper with a detailed 
description of these muscles because they have already been 
described by other authors. 
Differences between the Myomorpha and the Lagomorpha. 
1. In the Myomorpha the different parts of the temporal are 
closely connected. In the Lagomorpha the orbital part is large 
and much separated from the rest. 
2. In the Myomorpha the anterior deep part of the masseter 
passes through the infraorbital foramen. In the Lagomorpha 
there is no anterior deep part. 
3. The posterior belly of the digastric is well marked in the 
Myomorpha, in the Lagomorpha it is only present as a narrow 
tendon. 
4. The transverse mandibular muscle is present in the Myo- 
morpha, absent in the Lagomorpha. 
5. The omo-hyoid is present in the Myomorpha, absent in the 
Lagomorpha. 
6. The acromio-tracbelian (levator clavicule) rises from the arch 
of the atlas in the Myomorpha. In the Lagomorpha it rises from 
the basioccipital aud bifurcates below, one part going to the meta- 
cromion, the other to the clavicle and deltoid. 
7. The scalenus anticus is sometimes present in the Myo- 
morpha but absent in the Lagomorpha. 
8. The scapulo-clavicularis is absent in the Myomorpha, except 
the Bathyergine. It is present in the Lagomorpha. 
9. The three parts of the deltoid are fused in the Myomorpha, 
separate in the Lagomorpha. 
10. The biceps cubiti has two heads in the Myomorpha, one in 
the Lagomorpha. 
11. Among the Myomorpha the rotator humeri is only present 
in the Cricetine. In the Lagomorpha it is present in both rabbit 
and hare. 
12. The pronator quadratus is present in the Myomorpha, 
absent in the Lagomorpha. 
18. The clavo-cucullaris part of the trapezius is generally 
present in the Myomorpha, absent in the Lagomorpha. 
14. The splenius colli is absent in the Myomorpha, present in 
the Lagomorpha. 
15. The rectus abdominis frequently decussates with its fellow 
of the opposite side in the Myomorpha. In the Lagomorpha 
there is no decussation and the linex transverse are much better 
marked. 
