330 PROF. F. G. PARSONS ON THE 



marked cbaracteristics, and without tlie presence of some of ttese 

 no animal could be said to have hystricomorphine tendencies. 

 The chief of these characteristics are : — 



1. A large part of the masseter passes through the infra- 



orbital canal. 



2. The depressor mandibulae (digastric) has no well-marked 



central tendon, and the anterior bellies are not in contact 

 in the mid-line. 



3. The subclavius is continued past the clavicle to the supra- 



spinosus fossa to form a sterno-scapularis muscle. 



4. The flexor tibialis joins the flexor fibularis in the sole. 

 Anomalurus difi'ers from the last three entirely, and from the 



first in degree, but this is a point in which the Myomorpha 

 approach the Hystricomorpha. 



It will have been noticed that, in the absence of the omo-hyoid 

 Anomalurus differed from both the 8ciuromorpha and Myo- 

 morpha, while in the Hystricomorpha it must be stated that the 

 omo-hyoid may be present or absent. This may be looked upon 

 as a feeble hystricomorphine tendency, but it is just as strong 

 or as feeble a lagomorphine one. 



It seems unnecessary to take up space by a detailed com- 

 parison of the muscles of the Lagomorpha with those of Anoma- 

 lurus ; firstly, because no one has suggested any relationship 

 between the two, and, secondly, because I have never had the 

 opportunity of completing my knowledge of the myology of this 

 suborder by the dissection of a Pica. A general idea of the 

 relationship of Anomalurus to the four suborders of rodents as 

 illustrated by their muscles, may be gained by referring to the 

 accompanying table, and, in criticising it, it should be borne 

 in mind that the muscles have not been selected with any 

 reference to Anomalurus. They were chosen as the result of 

 previous dissections of many rodents, because they were found 

 to vary with the different suborders. It cannot be too strongly 

 insisted on that, if muscles are used for classificatory purposes, 

 they should not be chosen haphazard, nor should one or two be 

 used as crucial tests ; but, by careful comparison of a large 

 number of animals, some fifteen or twenty muscles should be 

 picked out which vary more or less constantly with the different 

 groups. The whole of these muscles should then be examined 

 in the animal whose aflBnities are to be tested, and the average 



