MYOLOGY OF ANOMALUEUS. 327 



The Plantaris expands in the sole into a muscular Flexor 

 Brevis Digitoriun. 



The Flexor Tibialis does not join the Flexor Fihularism. the 

 sole. This is a sciuro- and myo-morphine characteristic. 



The Accessorius is present, and is inserted into the plantar 

 surface of the flexor fibularis. In the Myomorpha the acces- 

 sorius is absent, but it is usually present in the Sciuromorpha. 



The Lumbricales closely resemble those of the fore limb, but 

 there are seven instead of six ; one rises from each side of the 

 tendons to the index, medius, and annularis toes, while the seventh 

 comes from the fibular side of the tendon to the hallux. 



The Deep Muscles of the Sole are arranged in two layers : the 

 superficial consists of an oblique adductor hallucis and minimi 

 digiti, while the deeper is formed by the double flexores breves 

 to each toe. The abductor hallucis and minimi digiti are the 

 enlarged and somewhat displaced marginal members of this series. 



Having given a brief survey of the myology of Anomalurus, 

 it remains to contrast these muscles with tliose of other rodents, 

 and to see whether they throw any lighb on the position and 

 relationship of this animal in the order. In the first place, it 

 will be well to review the chief myological characteristics of the 

 four suborders, and contrast them with those of Anomalurus. 



pTom experience gained in former dissections, 1 believe that 

 the following are the chief myological characteristics of the 

 Sciuromorpha : — 



1. The anterior deep part of the masseter lies in a groove in 



front of the zygomatic process of the maxilla. 



2. The digastric muscles have a central tendon from which a 



fibrous arcade stretches across the middle line ; to this the 

 anterior bellies are attached and they are in contact in 

 the mid-line of the chin. 



3. The transverse mandibular muscle is usually present. 



4. The omo-hyoid is present. 



5. The omo-trachelian muscle (levator claviculse) always rises 



from the atlas. 



6. The subclavius is never coutinued over the supraspinatus as 



a sterno-scapularis muscle. 



7. The coraco-brachialis brevis is always present, as are 



usually the medius and longus. 



