ALIMENTARY TRACT OF CERTAIX BIRDS. 77 



in rather stiff coils, which approach a spiral ; there are about three 

 of these, so that the gut is not long. It is quite difficult to 

 differentiate this gut from that of most Picopasseres. OMicnemus 

 (CE. SGolopax and CE. grallarius) hardly differs from Sarciophorus. 

 Of this genus I may, in the first place, i^emark that the pancreas 

 extends back to the very end of the duodenal loop. The attachment 

 of this loop to the ileic is as in Pluvianus. The ileic loop, more- 

 over, at any rate in CEdicneinics grallarius^ is very wide, another 

 point of likeness to Pkoviaiius and, indef^d, to other Limicolous 

 birds that will be mentioned presently ; indeed, in QiJ. scolopax 

 (see text-fig. 2.5) a separate ileic loop can hardly be defined — this 

 character, in fact, is of the group. In both species of the genus 

 (Edicnemus that I have examined the jejunum lies more or less 

 in a spiral, which is most marked in CE. gr^allarius, though it is 

 only a short spiral of one complete turn even in that species. 

 It is particularly to be noted that this spiral, like that of Passerine 

 birds, is not a permanent spiral, but that it can be pulled out to 

 form an irregular circle without tearing any mesenteries. The 

 genera which have just been dealt with are, in fact, not far 

 removed from the common ground-plan, and the steps of differenti- 

 ation are quite as is found in the great division of the Picopasseres. 

 A further stage of differentiation is seen in Recurvirostra 

 avocetta. Dr. Mitchell has correctl}^ commented upon the spiral 

 formation of the middle part of the gut, the jejunal region of the 

 nomenclature adopted in the present paper. 



This bird shows the typical Limicoline characters in {a) the 

 fact that the pancreas extends to the very end of the duodenal 

 loop, {h) in the wide ileic loop, which is about as long as the 

 duodenal, and (c) in the extent of the ileo-duodenal ligament. The 

 spiral is a fairly regular one, and although certainly not longer than, 

 and, I think, hardly as long as, that of the Raven, differs from it in 

 the important fact that it is a permanent spiral. The several coils 

 ai-e, indeed, connected together by mesentery and cannot be 

 separated out without tearing this mesentery. What is a tempo- 

 rary character in the more archaic forms of gut has here become a 

 permanent feature. 



The Lari of Dr. Gadow's classification, which I myself prefer 

 to associate more closely with the Limicolous birds, have an 

 intestinal ti-act which entirely justifies the latter placing. I have 

 examined Larti^s ridihundiis and L. argentatits among the Gulls. 

 In L. ridihundus the pancreas, as in Limicolous birds, extends to 

 the very end of the duodenal loop. The ileic loop is also wide 

 and is attached for the greater part of its length by the ileo- 

 duodenal ligament to rather more than the first half of the 

 duodenal loop. The whole of the jejunum, which is rather long, 

 lies in loose folds like the Mammalian small intestine, with no 

 fixed loops at all. I could not see any trace of a spiral arrange- 

 ment in this specimen. In L. argentatus, however, the jejunum 

 lay in a biggish loose spiral, which was not in any way permanent. 

 There is, in fact, no difference between these two species of Larus. 



