482 MANUAL OF ZOOLOGY sect. 



The left ovary (ov) is a large organ in the adult bird, its 

 surface studded with follicles or ovisacs, varying in size 

 from about 15 mm. in diameter downwards, and each 

 containing a single ovum. The left oviduct (I. od) is 

 long and convoluted ; its anterior end is enlarged to form 

 a wide, membranous ccelomic funnel (/. od") into which the 



todr 



Fig. 292.— Columba livia Male 

 urino-genital organs, adr, ad- 

 renal; cl 2, urodseum; cl 3, 

 proctodeum; k, kidney; is, 

 testis, that of the right side dis- 

 placed; ?ir, ureter; ur' , aper- 

 ture of ureter; rd, vas deferens; 

 vd' , its cloacal aperture; i>. s, 

 vesicula seminalis. (From Par- 

 ker's Zootomy.) 



Fig. 293. — Columba livia. Female urino- 

 genital organs, cl. 2, urodeum; cl. 3, 

 proctodeum; k, kidney; /. od, left ovi- 

 duct; /. od' , its cloacal aperture; hod", 

 its ccelomic funnel; /. od'", its ccelomic 

 aperture; ov, ovary; r. od, right oviduct; 

 r. od' t its cloacal aperture: ur, ureter; 

 ur\ its cloacal aperture. (From Parker's 

 Zootomy,) 



ripe ova pass on their liberation from the ovisacs ; the rest 

 of the tube has thick, muscular walls, lined with glandular 

 epithelium, and opens into the urodseum. 



Internal impregnation takes place. As the ova or 



