294 TROPICAL WILD LIFE IN BRITISH GUIANA 



is a single row of pigmented sheaths, superimposed by an- 

 other row of covert-hke sheaths. These are of special inter- 

 est as representing the pelvic wing recently demonstrated 

 by Beebe. ' 



A later embryo, probably not more than twenty-four 

 hours older, shows a further development of the tail and 

 body tracts. The spinal tract has become pigmented with 

 a light brown color, its sheaths being especially developed 

 along the dorsal region, M^iere some equal the rectrices in 

 length. No other pterylae are pigmented or much elongated. 



The spinal tract is (piite wide and divided by a long 

 cleft above the dorsal and sacral regions which unite at the 

 neck and lower pelvic. The femorals, accentuated by the line 

 of pigmented sheaths and their coverts, are large. They 

 join the crural or leg tract to form a continuous field, which 

 extends over the upper two-thirds of the cms and joins the 

 spinal pterylae behind the humeral tract above, and the ven- 

 tral just below the point of the sternum. 



The two scapular tracts are broad as in the adult and 

 the sternal is divided into two narrow banrls, one on each 

 side of the keel, the space between being very narrow and 

 extending from the point of the sternum to the upper throat. 

 The pectorals are wide and extend from half way between 

 the wing and the cms to tlie shoulder, wliere they join the 

 sternal. 



The embryonic pterylosis of the jacana more nearly 

 approaches the Limicoline type than that of the Fulicariae 

 as claimed by Nitzsch. In speaking of the adult birds, 

 Forbes says': "In their possession of well-marked firm rec- 

 trices, in the weakness of the lumbar tracts, and in the tend- 

 ency to a division of the dorsal tract into an anterior and 

 posterior fork, the Parridae differ from the typical Rallinae, 

 and approach the Ijimicoline type." These facts are in the 



^ Zoolot/ira, \'i)l. 11, No. 2. 



^ Notes on the Anatomy and Systematic Position of the Jaeanas ( I'arridae). 

 Proc. Zool. Soc. London, 1881, page 640. 



