26O MAY AGNES HOPKINS. 



1.50 mm. to 1.74 mm., the families Ciconiidae, Anatidae (Da- 

 fila, Aytliya, Chen, Nettion, Anser\ 



1.75 mm. to 1.99 mm., the families Spheniscidae, Phalacrocor- 

 acidse, and Anatidae (Qnergnedula). 



2.00 mm. to 2.22 mm., the families Carthartidae (Cartharista), 

 Gruidae, Phasianidae, Laridae (Sterna), Psittacidae. 



2.23 mm. to 2.46 mm., the families Ardeidae (Ardea), Cathar- 

 tidae (Carthartes\ Tetraonidae (Colinus), Laridae (Lams), Tyran- 

 nidae, Hirundinidae and Troglodytidae. 



2.47 mm. to 2.70 mm., the families Ardeidae (Nycticorax), 

 Tinamidae, Rallidae (Fulica, Ralhis], Charadriidae (ALgialitcs], 

 Scolapacidae (Tringa), Stercorariidae, Columbidae (Zenaidura), 

 Alcedinidae and Paridae. 



2.71 mm. to 2.94 mm., the families Falconidae (Bitteo), Picidae 

 (Dry abates, Colaptes), Tetraonidae (Colinns, Callipepla, Cyrtonyx), 

 Charadriidae (^.gialites), Turdidae, Scolapacidae (Tringa, Ca/idris, 

 Totanns, Sympliemid), Aphrizidae, Columbidae (Coin mba, Turtnr}, 

 Mniotiltidoe, Cuculidae and Tanagridae. 



2.95 mm. to 3.18 mm., the families Rallidae (Pore ana), Char- 

 adriidae (Sqnatarola), Scolapacidae (Erciinctcs), Icteridae, Capri- 

 mulgidae (Phalcenoptilus, Chordeilcs], and Fringillidae. 



3.18 mm. to 3.32 mm., the families Falconidae (Falco), Stri- 

 gidae and Scolopacidae (Numenius, Gallinagd). 



3.32 mm. to 3.56 mm., the families Charadriidae (Sqnatarola, 

 Cliaradrius), Caprimulgidae (Clwrdcilcs) and Picidae (Mclancrpes). 



4.33 mm., the family Trochilidae. 



These data show that birds of the most diverse forms of loco- 

 motion, and of very diverse affinities may show the same relative 

 sizes of semicircular canals. For example an excellent flyer, the 

 black vulture (Catkarista), and the poor flyers, the chicken (Ga/lns) 

 and the parrots (Psittacidne), have the same relative measurement, 

 1.98 mm. to 2.22 mm. Further, in certain families the genera 

 may exhibit great differences in these measurements, as particu- 

 larly in the Charadriidae and Anatidae. 



The relative sizes of the three semicircular canals to each other 

 may be summed up as follows : 



The anterior canal is always the largest. 



The posterior canal is larger than the exterior in all the follow- 



