1896.] MioliOat of RODftsras. 177 



Sacro-lumhalis and Longissimus Dorsi, — These muscles show 

 nothing remarkable in their attachments. 



Transversalis Capitis et Colli. — In Myoxus the trachelo-mastoid 

 or transversalis capitis was absent, in all the other animals both 

 muscles were found. 



Splenius Capitis et Colli. — The splenius capitis rises from the 

 ligamentum nuchse 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. 



Gomplcvm. — There is usually a slight tendency to longitudinal 

 division, but this is not seen in Oeorychus, Bathycrgus, Myoxus, or 

 jilyodes. Cricetus shows two intersections extending across the 

 whole muscle, while \nRhizomys 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 Eodents. 



Obliquus Exterwis Abdominis. — This muscle usually rises from 

 the posterior nine or ten ribs. The description already given 

 of it in the other Eodents 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 linesB 

 transverssB were seen extending across the muscle from the rectus, 

 while in Microtus the same thing was also noticed, but much less 

 distinctly. 



Obliquus Interims 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 as in 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 

 Muridte examined there was a decussation resembling that already 

 described in the Octodontidse ' ; this was not seen in Myoxus, 

 Oeorychus, or Bathyergus, though it was found in Rhizomys. 



Supracostdlis. — 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 Hiatus. — 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 

 regionas it does in the other Eodents. It is attached toall the lumbar 

 vertebrse except in the case of Rhizomys, where it only comes from 

 the first three. ■ 



' P.Z.S. 1894, p. 280. 



Paoo. ZooL. Soo.— 1896, No. XII. 12 



