GENITAL ORGANS 



473 



from its termination, each oviduct in Anurans becomes dilated to 

 form a thin-walled sac, in which the eggs, covered by a gelatinous 

 coating from the glands in the wall of the middle part of the 

 oviduct, become collected before oviposition : after again narrowing, 

 it usually opens separately on a papilla on the dorsal wall of 



n 



FIG. 356. URIXOGENITAL ORGANS OF A FEMALE Rana esculenta. 

 From the ventral side. 



X, kidneys ; Od, oviduct ; Ot, abdominal aperture of oviduct ; Or, left ovary 

 (that of the right side is removed) ; P, opening of oviduct into the cloaca ; 

 S, S l , apertures of urinary ducts into the cloaca, surrounded by longitudinal 

 folds (*), which are separated by a deep depression (t) ; Ut, the dilated 

 posterior end of the oviduct. 



the cloaca : in the genera Bufo and Alytes the two oviducts 

 fuse posteriorly into an unpaired canal. 1 



1 In Epicrhi m glutinosum (Gymnophiona) the ripe eggs are very similar to 

 those of Sauropsida : they are exceptionally large (9 mm. long), are of an oval 

 shape, possess a large yolk, and the segmentation is meroblattic, and takes place 

 in the oviduct. After fertilisation they become coated with tough albumen in 

 the oviduct, and this is drawn out at the poles into chalaza?, by means of which 

 che eggs are connected together like the beads of a necklace. The eggs are laid 

 in the earth, the mother coiling herself round them. 



