OP THE TONGUE OF PAEEOTS. 265 



Tabulation op the Chaeactees of the moee impoetant Muscles, and the Arrange- 

 ment OF THE Genera described, into Stages according to the Degree op 

 Development of the Tendon of the Ceratoglossus inferior. 



PA = Parahyal arch. 



PP' = Parah3-al process origin (primitive condition). 

 PP = Parahj-al process origin (secondary condition). 

 OE = Eiitoglossum. 

 HB = Hypobranchial. 



OL = The thyroglossus has lost its origin and lies free in the entoglossal concavity or is attached to 

 the membrane of the tongue. 

 OL & PP' = The thyroglossus has split and its origin is partly from parahyal process (primitive condition) 

 and partly it is as in OL. 

 — = Absent. 

 P = Present. ■ 



D = Divided. . . 



U = Single or undivided. 

 F.S. = Fairly strongly developed. 

 T.F. = Tendinous fascia. 

 W.T.F. = Weak tendinous fascia. 

 T.T. = Tendinous tract. 



S. =: Strongly developed. 

 V.S. = Very strongly developed. 

 B. = Broad. 

 Absent = Tendon or tendinous fascia absent. 

 CG.I.A'. = Liner portion of ceratoglossus inferior anticus. 



CG.L. = Ceratoglossus lateralis. 

 TH.H.A. = Thyrohyoideus accessorius. 

 HG.O. = Hypoglossus obliquus. 

 .TH.G-. = Thyroglossus. 



Extension along the whole length of the hypobranchial. 



s y Extension along that fraction of the length of the hypobranchial (anterior end implied). 



I _ 



1 _ 



4 ~ 



1-^ = A little less than f, but more than i. 



|-' = A little more than |-. 



= The inner portion of the ceratoglossus inferior anticus is most fully developed, and reaches not 



only to the middle line of the basihyal but extends back along the urohyal. (Retrogres.sion 

 has not commenced.) 



1 = As in 0, but does not extend back along the urohyal. 



II = That stage of retrogression when the muscle no longer reaches the middle line and does not 

 extend inwards more than about midway between I and III, i. e. midway between the tendon 

 of the ceratoglossus inferior and the middle line, 

 III = The inner portion has undergone complete retrogression, so that the ceratoglossus inferior 

 anticus does not extend to the inner side of its tendon (cg.i.a'. has wholly disappeared). 

 = Absence of ceratoglossus inferior posticus and implies a " unipars " type of muscle. 



