PHYLUM CHORD AT A. 



407 



as in the Lizard ; tbe narrow Eustachian tubes open by a common 

 aperture (Fig. 1040, eus. ap.) on the roof of the pharynx. 



Urinogenital Organs. — The kidneys (Fig. 1040, Jed, Figs. 1049, 

 and 1050, k) have a very characteristic form. Each is a flattened 

 organ divided into three main lobes and fitted closely into the 

 hollows of the pelvis. It is formed from the metanephros, the 

 large mesonephros or Wolffian body, which forms the embryonic 

 kidney, undergoing atrophy. The ureters (ur.) are narrow tubes 

 passing directly backwards to open into the urodiBum or middle 

 compartment of the cloaca. 



The testes (Figs. 1040, and 1049, ts.) are ovoid bodies, varying 

 gi-eatly in size according to the season, attached by peritoneum to 



Fig. 1049.— Columbalivia. Maleurino- 

 genital organs, adr. adrenal ; cl. ^, uro- 

 daeum ; cl. S, proctodseum ; k. kidney ; ts. 

 testis, that of the right side displaeed ; 

 ur. ureter ; wr'. aperture of ureter ; vd. 

 vas deferens ; vd'. its eloaeal aperture ; 

 V. s. vesicula seminalis. (From Parker's 

 Zootomy.) 



iHv-cM 



Fig. 1050.— Columba livia. Female urino- 

 •genital organs, c?.^, urodseum ; c/. 3, procto- 

 dseum ; Ic. kidney ; I. od. left oviduct ; I. od'. 

 its cloacal aperture ; I. od". its co3lomie funnel ; 

 I. od'". its cceloraic aperture ; ov. ovary ; r. od. 

 right oviduct ; r.od' . its cloacal aperture ; 

 v.r, ureter ; ur'. its cloacal aperture. (From 

 Parker's Zootomy.) 



the ventral surfaces of the anterior ends of the kidneys. From the 

 inner border of each goes off a convoluted vas deferens (vd.), 

 which passes backwards, parallel with the ureter, to open, 

 into the urodseum on the extremity of a small papilla. The 

 posterior end of the spermiduct is slightly enlarged to form a 

 ves'icula seminalis (v.s.). There is no copulatory organ. 



The female organs (Fig. 1050) are remarkable for the more or less 

 complete atrophy of the right ovary and oviduct. 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 



C C 2 



