INTESTINAL TRACT OF HTKDS. 



223 



f.illy with tlie figure. The diflerenecs which occur among the RallidjE are insignificaTit ; 

 in some, there are two " hridgiug " veins, in some, one; tlie Meckel's diverticulum, which 

 is always large, may he extremely large, the size of this structure heing a characteristic 

 feature of tlu; group ; the tlurd subsidiary loop of Meckel's tract occasionally is relatively 

 smaller than the other loops. 



(ilUMD.i:. 



(1) Gruiiuc. — In Griis virgo (fig. 12) and other species of (Iras, and species of 

 Avlhropoidvm and Balcarica are practically idcMitical, the large size has biouglit witli 

 it a relatively great increase of length, hut the fundanumtal ideutity of the coiilorniation 

 of the gut with that e.\hil)ited by the Rails is obvious. The duodenum is similar, 



i-'is. 42. 



liitcstiiinl 'I'riu t of GrMn v'ii-(\i). Lclteririf; as in tifr. 41. 



although, on account of its great length, it is partly bent. Meckel's tract displays the 

 same four loops : " a " being widened out ; " i," the axial loop Ijcing very loni;- hut carrying 

 a Meckel's diverticulum in 1 lie characteristic ])osition, on the distal linil) of the loop; 

 "r" being small but compound; and the supra-duodenal loop to which the huig cteca 

 are attached being much enlarged. It is plain that we have here a simple modification 

 of the Ralline pattern, the modification being due to the relatively greater length of gut 

 tliat occurs in larger birds. 



(2) Armnuio:. — The very interesting form Ara)}i,ns scolopuceus ilig. I.')) displays a 

 conformatiou of the intestinal tract which differs only in minor respects from that in the 



