148 WB. V. CHALMUES SlITOHELL ON THE [Jan. 14, 



deviation among the Pelargi, although Dr. Gadow has laid some 

 stress on the existence of such a resemblance. In some of the 

 A^ultures and Palcons there are spirals formed by the subsidiary 

 loops, just as occui-8, for instance, in Ciconia (tig. 9). On the 

 other hand, members of both groups exhibit a much 6im])ler 

 method of attaining increased length, and this seems to imply 

 that the spiral formation is a conA'ergent resemblance. When 

 the simplest members of the groups are taken — I am speaking 

 of them only from the point of view of gut-formation— the special 

 spiral formation disappears and the relations between the groups 

 are only their relations to the common type. The White-tailed 

 Sea-Eagle (fig. 12) shows the general character of the group. Its 

 gut is very long, and if the spiral twists were a character of the 



Fig. 12. 



Ilaliaetus albicilla ; inlestinul tract, x, Bhoit-circuiting vesBel divided. 



group one would expect the increased length to be displayed in 

 the formation of complicated spirals. This does not occur. The 

 duodenum is thrown into a complicated set of subsidiary loops, 

 thus recalling the similar modification in the Penguin. Among 

 the Accipitrines generally the duodenum is a very wide irregular 

 loop, but I have not found it thrown into secondary loops in other 

 eases. The circular loop forms a very extended set of minor 

 loops, some of which, especially on the lower side, are slightly 

 twisted into spirals. In other Accipitres it is more often the 

 upper loops of this series that are twisted. The vestige of the 

 yolk-duct occurs at the end of the median mesenteric vein in the 

 typical fashion, but is situated rather nearer the proximal end of 

 the loop. The last loop of the circular system is very long and 

 usually, as in Haliuiitus, spirally twisted. It gives a short-circuiting 

 vein to the duodenal vein. The part of the hind gut between the 

 Cfficaand the circular loop is thrown into a complicated set of folds, 



