194 BIRDS OP ILLINOIS. 



5. Sulida. Bill very thick through the base, bat tapering rapidly to the tip. 



which is very slightly curved, with the maxillary unguls faintly indicated. 

 Tail short (about half the wing), cuneate, the feathers narrowed toward the 

 end. 



6. Nostrils distinct (as in the Laridce); lateral toes nearly equal, and nearly as lone 

 as the middle: whole head normally feathered. 



6. PfiaethontidcB. Bill conical much compressed, the culmen curved; maxillary 



tomium very concave. Tail short, graduated, the central pair of rectricee 

 linear and excessively elongated. 



