312 THE MYOLOGY OF THE RAVEN. 



surfaces of all the vertebrae of the tail, except the 

 pygostyle. It is inserted into the quill-butts of the four 

 rectrices that lie next in order to the jDygostyle, which 

 insertion gives it the power of forcibly elevating these 

 four feathers by its contraction. 



151. Tlie transversus perinei^ arises, on either side, 

 from the entire posterior margin of the ischium, and 

 from the posterior margin of tliat portion of the post- 

 pubis which extends 1 )eyond it. This somewhat tendinous 

 origin makes a loop at the salient angle where the 

 ischium and ilium unite behind, through which loop 

 the femoro-caudal muscle passes. From this point of 

 attachment a dense fascia extends towards the coccyx, 

 being closely attached to the entire hinder margin of 

 the ilium, and firmly holding down the lower strata 

 of the coccygeal mucles. From this line of origin the 

 fibres composing the thin and sheet-like transversus 

 'pervnei converge and pass towards the median line, 

 to unite in a raphe with the muscle coming from the 

 opposite side, in front of the anus. 



These muscles serve to support the viscera here at 

 the lower part of the abdomen, and so, too, perform 

 the function of that muscle found in certain of the 

 Mammalia know^n as the levator aiii. 



152. The depressor caudcB is a strong conical muscle 



^ But few comparative morphologists seem to have designated 

 this muscle by the name I here bestow upon it, although Owen, I 

 believe, used it. Gadow {loc. cif., p. 129), presents us Avith the 

 following brief synonymy only, viz. : — 



" 22. M. TRANSVERSO-ANALIS. 



M. levator ani ; M. transversus ossium pubis. Gurlt, p. 20. 

 M. transverso-cloacalis. Gervais et Alix, p. 16. 

 „ ,, „ Watson, p. 71. 



Aufheber des Afters. Tiedemann, § 430." 



