196 MAYNIE R. CURTIS. 



these cases the enclosed egg was a membrane-covered egg with- 

 out any visible distinction between the poles. In each case the 

 enclosed egg contained a small irregular mass of yolk wrapped 

 in a mass of chalazal-like threads and surrounded by albumen. 

 In specimens 13 and 14 all of this albumen was thick, but in 

 specimen 15 both thick and thin albumen were present. In 

 each case the included egg had at each pole a bunch of chalaza- 

 like fibers resembling imperfect chalazse. In each case the 



FIG. 7. Diagram showing the structure of double egg No. 13. a = albumen; 

 c = chalazal-like threads; m = egg membrane; s = shell; y = yolk. 



including egg contained both thick and thin albumen. Evi- 

 dently in each case a dwarf egg which contained a small amount 

 of free yolk was returned from the isthmus to the uppermost 

 part of the oviduct and there furnished the stimulus for the 

 formation of the including egg. 



Specimen 16 is somewhat similar to the three eggs just de- 

 scribed. In this case the included egg did not contain yolk. 

 Neither were there visible chalazae at its poles. That is, a yolk- 

 less membrane-covered dwarf egg was evidently returned to 

 the albumen-secreting region where it furnished the nucleus for 

 the including egg. 



BRIEF DESCRIPTION OF FOUR DOUBLE EGGS FOUND IN THE 



BODY CAVITY OF A BIRD WITH AN ABNORMAL OVIDUCT. 



Beside the 16 specimens described above, 4 specimens were 



found in the body cavity of a bird with an abnormal oviduct. 



The case has been described in a previous paper (4). 'The 



oviduct was perfectly normal from the funnel mouth to the 



posterior end of the isthmus where the tube ended blindly. 



