544 DISCUSSION ON RESULTS RECORDED 



and part of the Rorlents, which migrated from South into Central 

 or North America. Birds, which, from their power of flight and 

 habit of migration common to a large number of them, are much 

 more easily distributed than most vertebrates, do not throw 

 the same light on geographical distribution as is the case with 

 more sedentaxy animals. This must, however, be applied in a 

 general sense, as many of the species are extremely local. Nearly 

 half the 1413 species are endemic; but a very large number are 

 migrants from the United States, spending the winter in Central 

 America and returning again in spring. There are, however, two 

 remarkable instances which I may mention. The family of the 

 Tinamidfe, which are essentially ground-birds, i-arely fly, and are 

 frequenters of the forest. Members of this family range from 

 Chili to Mexico. They are of a very ancient type, probably allied 

 to the Ratitse, and must have passed by land to Central America. 

 The Trogons, on the contrary, have a very wide distribution ; 

 they are strictly tropical, and are also frequentei"s of the forest, 

 but, unlike the Tinamidfe, have a very extended range, being also 

 found in Oriental regions, and a single species of a peculiar genus 

 occurs in Africa. Remains of a fossil Ti'ogon have been found in 

 the Miocene of France. 



It seems probable that South America may have had a land 

 communication with Africa at some remote period, and America 

 may have received some of its characteristic forms from that 

 continent. There is also some reason to suppose that there may 

 have been a land communication with Australia, though this 

 seems more remote. But this is a subject which 1 hope may be 

 discussed later. 



As regards the Insects, which form so large a portion of 

 the work, little can be said as to their distribution at present, 

 and it will be well to wait till more is known of those of other 

 countries ; at present the geological evidence is but scanty. 



Salvin and I had intended, on the conclusion of the ' Biologia.,' 

 to have discussed the geographical distribution of species, but in 

 consequence of his death and my own ill-health this project was 

 abandoned, and Mr. R. I. Pocock and Mr. Regan kindly came to 

 the rescue and I hope will be present here to-night. 



The total number of species recorded in the ' Biologia ' is 

 38,637 ; of these 19,067, or very nearly half, were previously 

 unknown. They belong to 1373 genera, and are illustrated by 

 1173 plates containing 18,051 species, mostly coloured. 



Although the ' Biologia ' contains the record of such a large 

 number of species, it is but a fragment of what may yet be 

 obtained. The whole work must be looked upon as only a con- 

 tribution to our knowledge of the subject, and I hope it may be 

 an incentive to others to carry it further. 



Dr. H. Gadow, F.R.S., F.Z.S., illustrated his necessarily very 

 condensed remarks by slides of maps showing the present physical 

 features of Mexico and Central America, and of hypothetical 



