of the Lesser Bird-of -Paradise. 447 



ventral tracts of " Seleucides alba," Epimachus superb us, 

 E. regius, and Diphyllodes magnifica. 



The differences between the two species of Epimachus 

 are surprisingly great, if these figures are correct, and still 

 more striking is the form of the spinal tract in Diphyllodes , 

 which, according to the figure, resembles that of the 

 Hirundinidse ! 



Nitzsch *, some years earlier, described very briefly the 

 spinal and ventral tracts of Paradisea apoda, Epimachus 

 superbus, E. regius, and Ptilonorhynchus holosericeus {vio- 

 la ceus), 



Epimachus superbus he found to differ from Paradisea 

 in that the spinal tract lacked the broad "saddle"; it 

 resembled Paradisea in that the outer branch of the ventral 

 tract passed insensibly into the inner, while in E. regius it 

 terminated freely as in Ptilonorhynchus. The saddle of 

 E. regius, it is curious to note, was cordate and bilobate 

 posteriorly. 



The Skin-muscles, and how they affect the Display. 



The display so vividly described by Mr. Grant is effected, 

 of course, by the harmonious working of a very complex 

 mechanism, but we are concerned here only with certain 

 agents thereof — the action of certain muscles underlying the 

 skin. 



The most important is one which, arising by a double head 

 from the side of the great pectoral muscle — described later 

 as the pectoralis abdominalis pars anterior, — is inserted into 

 the lower end of the great crowded mass of feathers which 

 forms the outer branch of the ventral tract. When this 

 muscle, under excitement, contracts, it necessarily draws the 

 roots of the mass of plumes concerned upwards and forwards 

 nearer the top of the back and towards the head. So long- 

 as this muscle remains tense the feathers will remain erect. 

 After the display they are drawn downwards by the con- 

 traction of a long band of muscle arising from the groin 

 and inserted into the end of the mass of plume-roots. The 



* Nitzseh, " Pterylography," Engl, Transl., Ray Soc. 1867. 



2h 2 



