370 MR. E. DEGEX ON ECDYSIS. 



DiAGK. K (stage of k). (Plate XXXVIll.) 



In specimen No. 25 the successive growth of metacarpo-digital remex X. or 

 stage k, and the last to be replaced for this series, we possess a particularly 

 Avell-defiued case of absolute bilateralism of symmetry. The development of this 

 flight-feather has reached exactly the same length on both sides. Its synchronous 

 equivalent on the cubitus, namely remex VI. or k', has also been developed in perfect 

 symmetry, having nearly obtained its full growth. The metacarpo-digital remiges IX., 

 also symmetrically developed on both corresponding portions of the wings, are yet 

 incomplete, though porportionately further advanced than X., and beautifully show the 

 regular order of their successive growth. This particularly typical specimen deserves 

 special attention. 



A glance at the diagram of this last specimen will at once disclose the fact that the 

 replacement of the flight-feathers, which at this stage is merely completed for the hand 

 portions, is incomplete for the cubitus, where a gap is left still for the filling in of 

 remex V., which is the last one to appear in this section of the wing. The earlier 

 accomplishment of the moult of the flight-feathers belongs, therefore, to the hand 

 portion, both in its initiating as well as its concluding stages. This is the case with 

 three specimens out of four which participate in this last phase. These are Xos. 24, 

 25, and 26 (left wing), and which have all been diagrammatized chiefly for showing the 

 growth of cubital remex V. in its earliest relationship to the others ; and lastly, No. 27, 

 which also shows a further case of perfect bilateral symmetry. It has been found 

 necessary to give a diagram of No. 24, because it shows the final stage in filling up 

 the gap by cubital remex V. Again, this stage, having practically no synchronous 

 equivalent on the hand portion as above mentioned, required the application of the 

 additional letter I' to mark this supernumerary condition. 



DiAGE. L (stage of /')• (Plate XXXVIII.) 



This represents specimen No. 26, and shows this stage in its beginning, the secondary 

 remex V. being of equal development on both wings. 



The growth of primary X. is nearly complete for the left wing ; whilst its develop- 

 ment on the right side is considerably retarded. 



DiAGE, M (supplementing stage of I'). (Plate XXXVIII.) 



As indicated above, specimen No. 24, though imperfect for the completion of the 

 moult on its hand portion, but otherwise very symmetrically developed, forms a case 

 for further progress in the final stage of I' or cubital remex V. It is curious to note 

 how early this specimen has reached this stage, being of February 18th, when com- 

 pared with 26th and 27th, which were both received a week later, namely March 4th. 



As already stated, the specimens completing the List of Birds examined, which 

 were received as late as the end of April, had their moult positively completed, 



