230 Mammalia. 



ternal to it, and very little below the margin of the Stylo- 

 glossus : the Whartonian duct should also be left in situ along 

 the lower margin of the Stylo- glossus. 



After removing the adipose tissue intervening between the 

 fascia of the under-lying muscles, the following arrangement 

 of the principal muscular strata will be disclosed. 



From the direction of the last molar tooth, towards the 

 H5^oid arch, just internal to the posterior part of the Stylo- 

 glossus, will be seen the obliquely-placed fibres of the Syo- 

 glossus, arising from the side of the body of the Hyoid (or 

 Basi-hyal), and inferior part of large cornua (or Thyro-hyals), 

 and inserted into the side of the Tongue : being in relation there- 

 fore externally, with the Stylo -glossus superiorly, and the 

 Mylo-hyoid and Digastric inferiorly ; crossed by the Hypo- 

 glossal nerve and Wharton's canal ; and in relation internally 

 with the two horizontal layers of muscles, next to be treated 

 of, viz., superiorly the Genio-h5^o-glossus, and inferiorly, next 

 to the median raphe, the Genio-hyoid. Just anterior to the 

 upper margin of the Hyo-glossus, and blending with it, will 

 be noticed a thin band of muscle getting thicker anteriorly, 

 situated on the under surface of the tongue between the Hyo- 

 glossus and the muscle next to be described, (viz., the Genio- 

 hyo- glossus), and whose fibres blend with the fibres of the 

 Stylo-glossus in front of the Hyo-glossus : this is the 

 external aspect of the Lingualis inferior muscle, one of the 

 intrinsic muscles of the tongue. 



Next there will be seen an upper stratum of longitudinal 

 fibres proceeding from within the anterior edge of the Hyo- 

 glossus and Lingualis, along the inferior surface of the tongue 

 to near the symphysis of the jaw. These are the fibres of 

 the GeniO'hyo- glossus muscle, which arises from the lateral 

 aspect of the inferior maxilla, near its symphysis, and is in- 

 serted first into the substance of the tongue, and further back 

 into the Cerato- and Epi-hyal bones (or lesser cornua) of the 



