AVES BIRDS. 617 



and female must, in the generality of species, be effected by a sim- 

 ple juxta-position of the sexual orifices : nevertheless, in the web- 

 footed tribes, which copulate in the water, and in the Ostrich, the 

 penis of the male is much more perfectly organized, as will be seen 

 by the following description extracted from Cuvier.* 



The structure of the penis is far from being the same in all birds 

 provided with such an organ : it offers, in fact, two types extremely 

 different from each other; whereof the Ostrich and Drake may 

 be taken as examples. The penis of the Ostrich is of a size pro- 

 portioned to that of the bird. Its form is conical ; and a deep, 

 narrow groove runs along its upper surface from the base to the 

 point. The vasa deferentia open into the cloaca opposite to the 

 commencement of the groove; so that the semen flows directly into 

 this furrow. This penis consists, first, of two solid conical bodies, 

 entirely composed of fibrous substance, supported at their base 

 within the sphincter of the cloaca upon its inferior wall. The 

 fibrous cones are placed side by side, but not confounded together ; 

 and the right is smaller than the left, no doubt to allow this organ, 

 which never becomes soft as that of quadrupeds, to be more easily 

 folded back into the cloaca. Secondly, of a fibro- vascular body, which 

 constitutes the bulk of the inferior aspect of the penis, and is con- 

 tinued to its extremity. Thirdly, of a cellular portion, capable of 

 erection, placed beneath the skin lining the urethral groove. This 

 last is doubtless the first appearance of the corpus spongiosum, 

 which in Mammifers completely encloses the canal of the urethra; 

 while the two others represent the corpus cavernosum. The whole 

 apparatus, when not in use, is drawn into the cloaca by two pairs of 

 retractor muscles. 



(688.) In Geese, Ducks, and many wading birds, such as the 

 Stork, the structure of the male intromittent organ is totally dif- 

 ferent. When in a state of repose, it is lodged in a pouch under 

 the extremity of the rectum, and curved, so as to describe three 

 parts of a circle. When the penis is opened in this condition, it is 

 found to be made up of two portions, each composing half of its 

 substance. The parietes of one half are thick, elastic, and slightly 

 glandular. The other presents internally a great number of trans- 

 verse grooves and folds. This latter portion during erection unrols 

 itself outwards like a glove ; and, at the same time, the half first 

 mentioned introducing itself into the hollow cylinder formed by the 



* Lejons d'Anat. Comp. torn. v. p. 108. 



