PICARIAN BIRDS. 871 



that three toes are turned forwards, wliile the latter signifies having all fonr toes 

 turned in that direction. The reader is now preiiarcd to understand the following 

 attempt at tabulating the chief characters of the Picarian sujier-faniilies : — 



Homalogonatous ; desmopelmoiis, Cnculoidem I ^^^^^ ^^^^^ ^^^^^^^^ ^^^^^^^ ^^^^ shou!de«. 



f Coracioideoi ) 



Anomalo- 

 gonatous 



X enters 



the iiiyo- 



loyical 



formula; 



synpehnous j CofioiJpd' ,• feet pamprodactylous j dorsaltract simple be- 

 Alceilinoidca: ; feet anisodaetylous ) tween the shoulders. 

 schizopi'liuous; Upupoidew ; dorsal tract furcate between the shoulders. 

 antiopolmous ; Pkoidc-m ; zygodactylous "j ,jorsal tract simple 



heteropelmous ; rro</0)iot(Zete; heterodactylous L between the 



shoulders. 



A alone constitutes the I ,,>vnnn 7.- 7.^ J^'""^™''*''^'""^' 

 myological formula; [ M^cropodou^e. \^ anisod^Jctylotts 



In regard to the above arrangement it nia^' l>e remarked that Sfcatornis is here 

 included among Coracioidca^, but tliat it is an easy matter to change the scheme so .'is 

 to accommodate a super-family, Steatornithoidea?, should it be thought advisable to 

 adopt such a division. 



The Picaria; form a group embracing upwards of eighteen hundred species, highly 

 characteristic of the tropical regions, for while the great majority of the families 

 composing it are "exclusively tropical, none are confined to, or liave their chief devel- 

 opment in, the temj)erate regions." The Neotropical region is richer in ])ecnliar fam- 

 ilies, but the total number of families represented in the Ethiojtean region is greater. 

 In regard to the many curious features of the geograi>hical distribution of the Picaria", 

 Mr. Wallace remarks : " We may see a reason for the great s])ecialization of this trop- 

 ical assemblage of birds in the Etliiopical and Neotropical regions, in the fact of the 

 large extent of land on both sides of the equator whicii these two regions alone pos- 

 sess, and their extreme isolation, either by sea or deserts, from other regions, — an iso- 

 lation which we know was in both cases much greater in early tertiary times. It is, per- 

 haps, for a similar reason that we here find hardly any trace of tiie connection lietween 

 Australia and South America which other groups exhibit; for that connection has 

 most jirobably been effected by a former C(mimunication between the temperate 

 southern extremities of those two continents. Tile most interesting and suggestive 

 fact is that presented by the distribution of the Megalaiinidae and Trogonidse over 

 the tropics of America, Africa, and Asia. In the absence of paleontological evidence 

 as to the former history of the Megalaimidie, we are unable to say positively wlicther 

 it owes Its present distribution to a former closer union between these continents in 

 intertropical latitudes, or to a much greater northern range of the group at the period 

 when a luxuriant sub-tropical vegetation extcmled far toward the Arctic regions; Imt 

 the discovery of Trogon, in the miocene deposits of the s<uitii of France, rcixlers 

 it almost certain that the latter is the true exidanation in the case of both these 

 families." 



The super-family CUCrLOIDE.E, being homalogonatous, desmopelmous, and 

 zygodactylous, is to all ai)]K-arance a natural group composed of two families, the 

 plantain-eaters and the cuckoos. The former are characterized by having tuftctl oil 

 elands and after-shafts to the contour-feathers, at the same time lacking colic cwca. 

 The cuckoos, on the other hand, lack tufts and after-shafts, but possess two ca-ca. 



In having small heads and a long neck, as also in the character of the plumage and 

 several structural features, the MrsoriiA<;ii>.i:, or ].lantain-eaters, resemble the Galli- 

 naceous birds, to which they certaiidy are not very distantly related. Indeed, the 



