160 MR. F. G. PARSONS ON THE [Jan. 14, 
The following is a list of the animals dissected for the first part 
of the present paper :— 
Myoxus dryas. Mus rattus. 
Gerbillus shawi. Mus barbarus. 
Cricetus frumentarius. Rhyzomys badius. 
Cricetomys gambianus. Georychus capensis. 
Microtus amphibius. Bathyerqus maritimus. 
Myodes lemmus. Heteromys longicaudatus. 
Mus decumanus. 
Also 
Lepus timidus and Lepus cuniculus 
for the sake of comparison. 
Accounts of the muscles of other animals by various authors 
have been used and their sources acknowledged in the text. 
Muscles of the Head and Neck. 
Temporal.—In all the Myomorpha the three parts of the tem- 
poral are more closely fused than they are in the Sciuromorpha, in 
this respect resembling the Hystricomorphine arrangement. 
In the Water-Vole the parietal part of the muscle is very large 
and arises from the temporal fascia, as well as the parietal, maxil- 
lary, and frontal bones. It runs down as a flat tendon to be 
inserted, opposite the anterior molar teeth, into the mandible. 
The anterior deep part of the masseter, after coming through the 
infraorbital foramen, joins this tendon. 
Fig. 1. 
PARIETAL part of TE 
' 
{ 
we, TEMP. 
| 
ANT.SUP.MAS. 1 
POST DEEP MAS, 
Masticatory muscles of Vole. 
In the Myoxide and Muride the muscles of opposite sides are 
separated by an interval which is often, as in Mus rattus, of 
considerable extent. In the Spalacide, on the other hand, the two 
muscles rise close together, and the superficial layer described by 
Allen! is distinct and rises by aponeurosis from the sagittal crest. 
These animals, moreover, bear out the statement in Broun’s 
1 Pr, Acad. Nat. Sc. of Philadelphia, vol. iii. p. 385. 
er eS hee ee eee ee lee 
ee 
