URINOGENITAL ORGANS 



371 



these organs show many points of resemblance with those of Reptiles 

 and Birds. 



Fio. 296. — A, Male Ueinogenital Organs of Omithorhynchus jMradoxun ; B, 

 Female Ukinogenital Organs of Echidna hystrix. 



I^, kidneys ; Ur, ureter ; B, urinary bladder ; Sikj, urinogenital canal ; Ho, 

 testis ; Ve, vas efferens ; Ep, epididymis ; Vd, vas deferens ; Od, oviduct ; 

 r, rectum ; CI, cloaca, opening to the exterior at Ci' ; m to iii\ muscles of the 

 cloaca and penis (or clitoris) ; Op, glans penis, enclosed within its fibrous 

 tube ; Pp, prepuce ; Cli, clitoris ; *, aperture through which the copulatory 

 organ extends into the cloaca. 



Thus in the oviparous Monotremes the left ovary is more strongly 

 developed than the right, and each has the appearance of a bunch 

 of grapes ; the cloaca persists, and the oviducts (Miillerian ducts), 



B B 2 



