DIGESTIVE SYSTEM 145 



All the Batitx agree in having the second loop right-handed, 

 and the thii'd left-handed ; this is a feature which occurs again only 

 in the Crypturi, Gallinse, OpistJiocomus, and in the Cuculidse. More- 

 over, as with the exception of the duodenum none of the loops are 

 closed and well defined, the Picditx represent in this respect the 

 lowest avine type. 



The Gallinse form a well-defined group ; lowest among them 

 stand the Neotropical Cracklx, through Avhich they lead towards 

 the Crypturi. The Gallinse have also an unmistakable resem- 

 blance to Opisthocomus and thence to the Ciiculidm. 



The Turnices, to which belongs undoubtedly Pedionomus, are 

 traceable to a Ralline or low Gralline stock, with assumed 

 plagiocoelous characters of the second loop. 



The pericoelous assemblage is large. It is typically represented 

 by the Waders, of which the Limicolx and the Pallidie form the 

 principal groups. 



The Rallidx with Otis and Grus are connected Avith the Turnices, 

 more distantly with the Cryptnri, and still more so with Apteryx. 

 Dicholophus is in all points a Gruine form, like Fsophia, and cannot 

 be separated from them. Bhinochetus contains Ealline, Limicoline, 

 and Iliis-like features ; the only bird which it resembles somewhat 

 closely in its very peculiar intestinal convolutions is Podica. 



The Limicolx agree with the Laridse, and also with the Columhai 

 in all essential points. Each of these three groups contains a number 

 of forms Avhich lead in an unbroken series from the typically peri- 

 coelous birds with four alternating loops to the typically mesogyrous 

 birds. Most Columbx and Laridx are mesogyrous, but Sterna and 

 its allies represent pericoelous or lower forms. Neither granivorous, 

 nor insectivorous, nor piscivorous habits have exerted any appreciable 

 influence upon their intestinal convolutions, although of course the 

 stomach and the cseca are affected. The presence of the crop of the 

 Columbm is repeated in the granivorous Limicoline genera Attagis 

 and Thinocorys. 



Numenius approaches in various ways the Ibises, whence a con- 

 tinuous line can be traced into Platalea and Phoenicopteriis on the one 

 hand and into the Pelargi proper on the other. 



Eather different from the Limicohv are the Pterodidse. They 

 have four loops, which are all closed, lef1>handed, i.e. isocoelous, and 

 straight ; the second and fourth loops have their apices turned back, 

 and especially the terminal end of the second resembles somewhat a 

 plagiocoelous formation. The Pterodidse have consequently various 

 points in common with the Pallidse, Limicolse, and Cohtrnbx. 



The Alcidai are pericoelous and strictly orthocoelous ; they agree 

 with the Laro-Limicolai in the configuration of their first three loops, 

 but they differ from them in the number of loops, Avhich is at least 

 six, the last three of which are left-handed. They approach in this 



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