178 MR, EF, G. PARSONS ON THE [Jan. 14, 
Muscles of Posterior Extremity. 
Gluteus Maximus, Tensor Fascie Femoris, and Sartorius.—The 
description already given‘ applies perfectly to the Myomorpha; the 
tensor fascie and sartorius are, however, as a rule less well marked, 
and there is also a closer union between the posterior border of the 
gluteus maximus and the anterior border of the biceps femoris. 
The bony insertion of the gluteus maximus is into the middle of 
the femur except in Cricetus, where it is also attached to the 
external supra-condylar ridge of the femur, and in Rhizomys, 
where it is attached almost entirely to the third trochanter in the 
upper part of the bone. The sartorius and tensor fascie femoris 
are best marked in Cricetus, while in Georychus they are practically 
absent. 
Gluteus Medius and Minimus.—These muscles present no 
differences from those already described in other Rodents. 
Scansorius.—The scansorius is so closely fused with the gluteus 
minimus, that it is only possible to make it out as a distinct muscle 
in Cricetomys, though even there the separation is not very 
clear. 
Pyriformis.—This muscle is also much more closely fused with 
the gluteus minimus than in the other Rodents; indeed, the 
Myomorpha are remarkable for the unsatisfactory differentiation 
of the muscles composing the gluteal mass. 
Obturator Internus, Eaternus, and GemelliicThese muscles 
correspond to their descriptions in the other Rodents. The 
anterior gemellus is always better marked than the posterior 
one. 
Quadratus Femoris——There is usually a very slight tendon at 
the insertion, the muscle being triangular as in the Hystricomorpha 
and differing from the quadrilateral Sciuromorphine type; it is 
always large and distinct. 
Biceps Femoris.—In Myowxus, Mus barbarus, and Mus rattus the 
two parts of which the biceps is composed are closely united and 
have one continuous insertion, as is the case in the Hystricomor- 
phine Rodents. In the other Myomorpha the two parts are easily 
separable, as they are in Sphingurus*. When this happens, it is 
the upper part which rises from the anterior caudal vertebrae and 
is inserted into the outer side of the patella and ligamentum 
patella, while the lower part rises from the tuber ischii and is 
inserted into the fascia on the outer side of the leg. In certain 
cases, e. g. Cricetomys and Myodes, the upper portion is very closely 
connected to the gluteus maximus; while in Cricetus it is so 
closely blended with that muscle, that it has already been described 
as a part of the gluteus maximus which is inserted above the 
external condyle of the femur. 
In Georychus, Bathyergus, Rhizomys, and Heteromys the two parts 
are separate from one another and from the gluteal. 
1 P.Z. 8. 1894, p. 282. 
2 P.Z.S. 1894, p. 284. 
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