DIGESTIVE SYSTEM 147 
The Pelargi are often classed with the Herod, but these two 
Families differ from each other in almost every point of primary 
importance. 
There are also certain resemblances between the Pelargi and the 
Accipitres, the chief connexion is formed by the telogyrous character, 
the mode in which additional loops of the lengthened gut are stowed 
away, and the tendency to convert some or one of the principal 
loops into regular spirals. Among the Accipitres, the Old-World 
Vultures especially exhibit striking Ciconiine similarities. As 
regards the Cathartidzx, I have to deplore want of material. 
The Psittact are distinctly telogyrous ; all their five principal 
loops are closed and alternating ; this, with the presence of a crop, 
and the absence of functional ceca, are features which occur again 
together only in the Accipitres. The absolutely vegetable food of 
the Parrots would sufficiently account for the differences which exist 
between them and the entirely zoophagous Accipitres. However, 
this indication of a possible relationship between the Birds-of-Prey 
and Parrots is as little binding or satisfactory as other suggestions 
based upon other organic systems. 
Of the Coccyges the Cuculide possess four intestinal loops, of 
which the first and second are right-handed. The loops are on the 
whole orthoccelous, but the apices of the two middle ones are often 
turned up, or the second loop is plagioccelous. Moreover, they 
possess fully-developed ceca. In all these respects they resemble 
to a great extent the Gallinw; and this hint is considerably 
strengthened by Opisthocomus, which is, barring special features, 
exactly intermediate between the Cuculidz and the Gallinw. The 
Musophagidex seem to possess but three loops, the original second 
loop having been suppressed in connexion with the frugivorous 
habits of these birds. The isoccelous feature of the Musophagidx is 
therefore reduced to a secondarily acquired one, and to a case of 
convergence towards the typically isoccelous birds. 
The Pict (Picidx, Capitonidx, and Rhamphastidx) differ, like tho 
Epopes (Bucerotidx, and Upupidx), from all the remaining birds in 
the alternating position of their four loops, which in the frugivorous 
Ehamphastidz, as well as in the extremely short-gutted genus Upupa, 
are reduced to three by the suppression of the original second loop. 
Xantholema, one of the Capitonidx, has this second loop still indicated. 
The total absence of ceca in all these birds is a coincidence, while 
there are no obvious characters, besides the anticcelous convolutions, 
which point to a close relationship between the Pici and the Epopes. 
The remaining birds are all isoccelous. Of them the Coraciidze 
stand nearest to the hypothetical ancestral or central stock, because 
they are the most generalized group, from which all others can be 
derived. The Alcedinidx, which have reached a truly mesogyrous 
formation, started in one direction from or out of the Coraciidzx. 
