XIII 



PTIYLUM CHORD AT A. 



407 



as ill the Lizard ; the iianow Kustacliiaii tubes o))eii by a cumniuii 

 aperture (Fig. lO-iO, eics. ap.) on the roof of the pharynx. 



Urinogenital Organs. — The /.vV^m«/s (Fig. 1040, bf, Figs. 1049, 

 and IdoO, A-) have a very characteristic form. Fach is a flattened 

 organ dividetl into three main lobes and fitted closely into tiie 

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

 large niesonephros or Wolffian body, which forms the embryonic 

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

 passing directly backwards to open into the urod;eum or middle 

 compartment of the cloaca. 



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

 greatly in size accordiDg to the season, attached by peritoneum to 



or 



Fio. HM'.t.— Columbalivia. Male urino- 

 genital urguns. I"//-, adrenal; rV. 2, uro- 

 djKum ; !■/. -J, proctudieuui ; I: kidney ; ta. 

 testis, that of the right side displaced ; 

 ur. ureter; v.r'. aperture of ureter; v<>. 

 vas deferens ; vd'. its cloacal aperture ; 

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

 Zootoiin/.) 



-,. Loci' 



Fir.. IO.'jO.— Columba livia. Female urino- 

 genital organs, rl. .', unnlaniin ; cl . ■', procto- 

 da;um ; A', kidney ; /. od. left oviduct ; /. od' . 

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

 I. od'". its eielomic aperture ; ov. ovary ; /■. od. 

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

 ?(/'. ureter; ur'. its cloacal aperture. (From 

 Parker's iiootom//.) 



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

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

 which passes backwards, parallel with the ureter, to open 

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

 posterior end of the spermiduct is slightly enlarged to form a 

 vesicula 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 liift ovary 

 (av.) 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 



