358 University of California Publications in Zoology V^oi.. 13 



In the Laridae and Aleidae the down barbules are shorter, with 

 indistinct nodes on the proximal portion, and well-developed prongs 

 distally, thus very closely resembling the Colymbiformes. 



d) Relationships 



The unquestionable likeness of the structure of feathers in the 

 Aleidae to that in the Colymbiformes very strongly suggests the 

 close relationship between them. The relation of the Laridae to 

 the Aleidae, and of the Limicolae to the Laridae, is just as plainly 

 indicated, and we have a very clear and distinct path of evolution 

 suggested by these groups. Eelationship to the Gruidae is also 

 suggested and it is probable that the latter represent an early off- 

 shoot from the limicoline stem. The Limicolae, in all respects, show 

 higher specialization than the other forms included in the suborder, 



e) Summary 



The Laro-limicolae are characterized as follows : 



(1) Plumules evenly distributed, though sometimes sparse in the 

 Limicolae. 



(2) Aftershaft present, sometimes small. 



(3) Distal barbules of remiges with broad subnuclear area on 

 base, very small ventral teeth, rather short, subequal booklets, a series 

 of subequal, somewhat curved ventral cilia, and on inner vane two 

 proximal dorsal cilia more or less earlike. 



(4) Proximal barbules with very slender base, inconspicuous 

 ventral teeth, and pennulum little if any over half length of base; 

 proximals of outer vane with imperfectly developed ventral cilia. 



(5) Distal barbules of back feathers with a long series of well 

 developed, curved, ventral cilia. 



(6) Breast feathers with barbules on outer portion of barbs with 

 flexules. 



(7) Down resembling that of Colymbiformes in Laridae and 

 Aleidae, the barbules with enlarged nodes and more or less pig- 

 mented in Limicolae. 



Suborder Pteroclo-columbae 

 Plate 29 

 This suborder includes two rather distinct and well-defined 

 groups, the Columbae with the pigeons and doves on the one hand, 



