1901. 



ANATOMY OF GllUIFOBM BIllDS. 



631 



degrees of specialization of anatomical conditions. I distinguished 

 one condition of character found in a group as being, with regard 

 to that group, archecentric, that is to say as most nearly representing 

 the ancestral condition or common heritage of the group ; while 

 the other conditions were distinguished as apocentric, that is to 

 say as having moved outwards along some radius from the arche- 

 centric condition. In this terminology, I regard the diastataxic 

 condition of the wing as archecentric, the eutaxic condition not 

 only as apocentric but as multiradially apocentric — that is to say, as 

 being an instance of such a simple and direct change as we may 

 imagine to have occurred independently in different cases. In 

 Columbidse and Alcedinidse there is a general coincidence of this 

 apocentricity of the wing with apocentricities of other structures. 

 The problem of the present research was to see to what extent 

 and in what structures there was a similar correlation of apo- 

 centricities in Gruiform birds. It is clear that the field of the 

 problem is essentially different ; there is no doubt as to the close 

 genetic affinity of the different Doves and Pigeons, and the King- 

 fishers are a group at least equally coherent. In the case of the 

 birds here associated as Gruiformes, there are many taxonomic 

 uncertainties, among which the least uncertain point is, that 

 even if the assemblage be natural, many of the groups assigned to 

 it stand far apart. 



EUTAXY AlSri) DiASTATAXY IN THE GeUIFOEMES. 



Rallidce. — All the Rails that I have examined have the wings 

 typically diastataxic. The condition in Rallus longirostris (text- 

 fig. 70) may serve as a type. The primary quills have major coverts 



Text-fig. 70. 



Wing-structure of Rallus longirostris. 



Diagram of the distal secondary quills and coverts, showing the diastataxic 

 condition. The quills are in outline ; the major coverts and " third- 

 series" feathers are in blact: the transverse rows are represented by 

 dotted lines with larger black dots showing the positions of feathers. 



iS. First secondary. P. First primary. x. Diastataxic gap. C.R. 

 Carpal renies. (J.C. Carpal covert. 



