of the Lesser Bird-of -Paradise. 451 



Comparative Myological Remarks. 



I have carefully compared the dermal muscles of Paradisea 

 minor with those of its near allies P. apoda, Ptilorhis para- 

 disea, and Manucodia comrii, as well as — for the sake of 

 shewing the range of variation of the muscles in question — 

 with Ptilonorhynchus violaceus, Sericulus melinus, Corvus 

 corone, and Pityriasis gymnocephala. 



Paradisea minor and P. apoda differ only in that the two 

 heads of the pectoralis abdominalis pars anterior are inserted 

 nearer together in P. minor than in P. apoda. ^he close 

 relationship which obtains between these two forms naturally 

 leads one to expect but slight differences in this matter. The 

 accessory head of the pars anterior is found only in these 

 two species, and is to be attributed to the enormous develop- 

 ment of the pectoral plumes which these muscles have to 

 drag upwards and forwards and hold in position during the 

 display. 



The pectoralis abdominalis is normally formed by a single 

 band of muscle extending from the pubis, and running along 

 at first beneath the inner branch of the pteryla ventralis it 

 turns upwards and crossing the free end of the outer branch 

 of this tract it is ultimately inserted into the dorsal border of 

 the pectoralis in the region of the axilla. Thus it will be 

 found in Corvus. In Ptilonorhynchus and Sericulus this 

 band breaks up into two, connected only by a few slender 

 fibres. The posterior part, as will be seen in text-fig. 32 

 (p. 119), becomes firmly attached to the free end of the outer 

 branch of the pteryla ventralis ; the pars anterior similarly 

 becomes attached to a slight angulation of the dorsal border 

 of this feather-tract. 



In Sericulus the pars anterior and pars posterior are some- 

 what less distinctly separated, the divided ends being placed 

 closer together to form a sharp angle with one another 

 (text-fig. 32). 



In Manucodia comrii and Pityriasis gymnocephala the 

 variation is slightly more marked. In the first-mentioned 

 the outer branch of the y>/. ventralis turns slightly upwards, 



