OCR Text |
Show 1879.] MR. W. A. FORBES ON THE GENUS LATHAMUS. 169 the widest part, the feathering being rather strong and not close. in most Parrots, there are two humeral tracts. The space on the carina sterni between the inferior tracts of the two sides is not wide. There is a well-marked outer pectoral tract, about 1 inch long, distinguished by its rather stronger and closer feathering. It is quite separate from the main part of the inferior tract, the space between the two tracts being about as broad as the latter tract itself. The outer pectoral has the appearance of being somewhat dilated at its free end, owing to the presence of a few irregularly placed and small feathers lying to the outside of its termination. The main part of the inferior tract is rather narrow, with its rows of four and five feathers each separated by rather considerable spaces. The scapular fork is rather long, the tracts being narrow and moderately strongly feathered. The dorso-lumbar fork is elongated ; each arm is of nearly the same strength and breadth throughout, beginning a little outside the scapular fork, with the part inside the arms of the latter represented only (as usual in the Psittaci) by one or two rows of small feathers, placed singly or in pairs. Each arm is composed of about fourteen rows of feathers (counting to the junction with its fellow), the rows being four feathers wide, rather close together, and of about the same width as the space between the tracts. There is some tendency in some of the anterior rows towards a dilatation of the tract, one or two of the rows being five feathers wide. In the more anterior parts of each arm, the most internal feather of each row is often placed in front of and at an angle with the other feathers composing it, and so comes to stand between two rows of three feathers each; so that at first each tract looks as if made up of rows of three (or four) feathers alternating with single feathers. This tendency to a 3.1.3 arrangement, however, disappears in the the more posterior parts of the tracts, the four feathers of each row there standing in a direct line with one another. The two arms unite to form the "handle" at about three quarters their entire length ; after the junction the tract narrows rather rapidly towards the tail. The dorso-lumbar fork is throughout quite distinct from the lumbar feathering, which is very weak and diffuse. In all the truly Platycercine1 forms that I have examined-namely Platycercus eximius and pennantii, Psephotus heematogaster (four specimens) and P. hcematonotus, Pyrrhulopsis splendens and P.perso-nata, Cyanorhamphus auriceps and C. novee-zealandiee-the disposition of the outer pectoral tract and dorso-lumbar fork resembles essentially that of Lathamus. In all the outer pectoral is a distinct, more closely feathered, and rather narrowish tract, clearly separated throughout from the main part. In Cyanorhamphus this tract is distinctly hook-like, dilated at the end. In all the same length2, and uniformity in strength and width, of the arms of the dorso-lumbar 1 I. e. excluding Aprosmictus, Polyteles, Euphema, Pezoporus, &c. 2 In Pe. pennantii, and in the two species of Pyrrhulopsis I counted fourteen, in C. auriceps thirteen, in Ps. hcematonotus thirteen, and in Ps. heematogaster eleven rows of feathers in the arms of this tract to their junction. |