PIC ASIAN BIRDS. 371 



that three toes are turned forwards, while the latter signifies having all four toes 

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

 attempt at tabulating the chief characters of the Picarian super-families : 



Homalogonatous ; desmopelmous, Cuculoidev I dorgal ^ furcate ^^ ^ shoulderg 



(Coracioidece ) 

 Colioidece ; feet pamprodactylous j dorsal tract simple be- 

 Alcedinoideoe ; feet anisodactylous J tween the shoulders. 



Anomalo- 

 gonatous 



X enters 



the myo- 



logical 



formula; 



schizopelmous; Upupoideos ; dorsal tract furcate between the shoulders. 



antiopelmous ; Picoidece ; zygodactylous 

 heteropelmous; Trogonoidece ; heterodactylous 



A alone constitutes the ) MicropodoidecB I P-P-dactylous J 

 myological formula; J j anisodactylous J 



dorsal tract simple 



between the 



shoulders. 



In regard to the above arrangement it may be remarked that Steatornis is here 

 included among Coracioideae, but that it is an easy matter to change the scheme so as 

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

 adopt such a division. 



The Picariae 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 have their chief devel- 

 opment in, the temperate regions." The Neotropical region is richer in peculiar fam- 

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

 In regard to the many curious features of the geographical distribution of the Picariae, 

 Mr. Wallace remarks : " We may see a reason for the great specialization of this trop- 

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

 large extent of land on both sides of the equator which 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 the connection between 

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

 most probably been effected by a former communication between the temperate 

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

 fact is that presented by the distribution of the Megalaimidae and Trogonidae over 

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

 as to the former history of the Megalaimidae, we are unable to say positively whether 

 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 extended far toward the Arctic regions ; but 

 the discovery of Trogon, in the miocene deposits of the south of France, renders 

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

 families." 



The super-family CUCULOIDEJE, being homalogonatous, desmopelmous, and 

 zygodactylous, is to all appearance a natural group composed of two families, the 

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

 glands and after-shafts to the contour-feathers, at the same time lacking colic caeca. 

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



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

 several structural features, the MTJSOPHAGID^E, or plantain-eaters, resemble the Galli- 

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



