1896.] MYOLOGY OF RODENTS. 177 
Sacro-lumbalis and Longissimus Dorst.—These muscles show 
nothing remarkable in their attachments. 
Transversalis Capitis et Collii—In Myowus the trachelo-mastoid 
or transversalis capitis was absent, in all the other animals both 
muscles were found. 
Splenius Cupitis et Colli.i—The splenius capitis rises from the 
ligamentum nuchz nearly as far forward as the occiput, and 
almost entirely covers the complexus; it has the usual attachments. 
The splenius colli was not seen at all. 
Complewus.—There is usually a slight tendency to longitudinal 
division, but this is not seen in Georychus, Bathyeryus, Myowus, or 
Myodes. Cricetus shows two intersections extending across the 
whole muscle, while in Rhizomys they only extend across the outer 
half of it. 
Tail-Muscles.—In those animals which have tails, the arrange- 
ment of the muscles is the same as in other Rodents. 
Obliquus Externus Abdominis.—This muscle usually rises from 
the posterior nine or ten ribs. The description already given 
of it in the other Rodents applies to the Myomorpha, with 
the exception that it never runs upward to the first rib with 
the rectus. The outer pillar of the abdominal ring is large 
and muscular, and is inserted into the whole length of the 
body of the pubes, external and parallel to the symphysis. The 
inner pillar is thin and fascial. In Cricetomys five or six linee 
transverse were seen extending across the muscle from the rectus, 
while in Microtus the same thing was also noticed, but much less 
distinctly. 
Obliquus Internus and Transversalis.—These muscles can be 
separated with great care. In Bathyergus they are very well 
marked, and in that animal the relation of the aponeurosis to the 
rectus can be made out, and is found to be asin Man. In Mus 
rattus the scrotal pouches are very large, and are composed entirely 
of the internal oblique. 
Rectus Abdominis—In all the specimens of the family of 
Muride examined there was a decussation resembling that already 
described in the Octodontide'; this was not seen in Myoaus, 
Georychus, or Bathyergus, though it was found in Rhizomys. 
Supracostalis—In no Rodent was this muscle seen. 
Psoas Parvus.—The psoas parvus was present in all the 
specimens except the Gerbille; in Microtus, Rhizomys, and 
Georychus, however, it was small. 
Psoas Magnus and Iliacus.—These muscles have the usual rodent 
attachments. 
Quadratus Lumborum.—In most of the Myomorpha the quadratus 
lumborum does not seem to rise from as far forward in the dorsal 
region as it does in the other Rodents. It is attached toall the lumbar 
vertebre except in the case of Rhizomys, where it only comes from 
the first three. 
1 P.Z.8. 1894, p. 280. 
Proc. Zoou. Soc.—1896, No. XII. 1 
