4 oo SCIENCE PROGRESS. 



Of these perhaps the most important is Archczotrogon, 

 which is closely related to the Trogons, and may indeed be 

 an ancestral form of the genus Trogon, an extinct species 

 of which has been recorded from the Miocene of Allier. 

 At the present day these birds occur in the Neotropical, 

 Ethiopian, and Indian regions ; and it is remarkable that 

 the extinct Miocene bird of Southern France should belong 

 to a Neotropical genus rather than to one of those found in 

 the Old World. This peculiar distribution of the recent 

 and fossil forms is shown in a still more marked manner 

 in the case of the next genus, Filholornis, which is said 

 to be closely allied to Opisthocomns. The only known 

 representative of this genus is the Hoatzin (Opisthocomus 

 cristatus), which is one of the most peculiar and isolated 

 forms of Carinate birds now living. It occurs only in 

 Guiana and the Amazonian region, and is referred to a 

 separate sub-order of which it is the only member. It is 

 usually regarded as a primitive type, and the occurrence 

 in Europe of a closely related bird is, therefore, another of 

 those numerous cases in which such generalised types, now 

 found only in the Southern hemisphere, have extinct re- 

 presentatives in the Northern. That the determination of 

 the affinities of Filholornis is correct there seems to be no 

 doubt, since Milne Edwards states that its ulna is almost a 

 facsimile of that of the Hoatzin, in which that bone is of a 

 peculiar and distinctive form. 



In the same memoir several new ralline birds are added 

 to the already numerous rails recorded from the Tertiaries 

 of France. One of the new forms, Rallus dasypus, though 

 much smaller, is said to resemble Ocydromus in the form of 

 its humerus ; and another, Elaphrocnemus, a new generic 

 type, approaches Aphanapteryx in the structure of its meta- 

 tarsus. The occurrence in the lower Tertiary deposits of 

 Europe of a large number of rails seems to be rather a 

 strong argument in favour of a northern origin of the group, 

 which, as Milne Edwards points out, is an extremely ancient 

 one, of which at the present day we are only acquainted with 

 some more or less degenerate descendants. Many of the 

 more modified forms, such as Ocydromus and Aphanapteryx, 



