184 MR. F, G. PARSONS ON THE (Jan. 14, . 
3. The gracilis isa single muscle. 
4, The flexor tibialis joins the flexor fibularis in the sole. 
5. There are only three lumbricales in the foot. 
6. There is an adductor hallucis instead of an adductor indicis 
in the foot. 
Whether the rectus abdominis decussated with its fellow of the 
opposite side, could not be determined owing to the large incision 
which had been made for evisceration before the specimen came 
into my hands. 
The family of the Muride is represented by accounts of the 
dissection of nine animals, and I am only able to discover one mus- 
cular peculiarity which is common to them all and at the same 
time distinguishes them from other families,—this is the fact that 
the rectus abdominis always decussates with the muscle of the . 
opposite side. When one considers what a large and _hetero- 
geneous family this is, and that many of the genera included in it 
are only placed there provisionally, one is not surprised to find 
that their musculature is not nearly so consistent as it was found 
to be in the different families of the Hystricomorpha. 
To my mind the fact that the latter show definite muscular 
characteristics which are not found in the former, indicates that the 
hystricomorphine families consist of animals which are more nearly 
allied to one another than is the case in the Muride: in other 
words, that the classification of the Hystricomorpha is more success- 
ful than that of the Myomorpha. 
While speaking of the Muride, it is worth noticing that Cricetus 
and Cricetomys are the only two of the Myomorphaexamined which 
possess the first part of the coraco-brachialis or rotator humeri 
muscle. In many particulars, however, they differ from one 
another. 
In the family of the Spalacide there are records of three animals, 
Bathyergus, Georychus, and Rhizomys. The following points of 
resemblance were noticed in this group :— 
1. The temporals are large and meet in the middle line of the 
head. : 
2. The stylo-hyoid and stylo-glossus are closely blended in 
Rhizomys, while in Georychus the stylo-hyoid is absent or completely 
fused with the other muscle. 
3. The pronator quadratus is very feeble. 
4, The reflected head of the rectus is ill-marked. 
5. The gastrocnemius has no fabelle in its tendons of origin. 
6. There are three lumbricales in the foot. 
The following are points of difference between Rhizomys on the 
one hand and Georychus and Bathyergus on the other :— 
1. In Rhizomys the digastric has a well-marked central tendon, 
in Bathyergus and Georychus there is only an intersection. 
2. In R. the cleido-mastoid is overlapped by the first part of the 
trapezius ; in B. and G. it is not. 
3. In B. and G. the scalenus anticus is present. In A. it is 
absent, as it is in all other Myomorpha except Gerbillus. 
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