582 



ANATOMY OF VERTEBRATES. 



ortriii^ of Emus cuyojKca. xxxviir. 



391 



larger than in the marine species : it is sul^cylindrical, with an 

 expanded terminal glans, il:). I, usually ending in a point. The 



urethral groove, ib. G, 

 ^ ^° extends along the mid- 



dle of the dorsal surface, 

 and becomes deeper as 

 it approaches the glans : 

 in erection the tumefac- 

 tion of its borders con- 

 verts the groove into a 

 temporary canal, and it 

 then a}i2'>ears to end by 

 an orifice, k, which is 

 usually divided by a 

 jiapillary eminence. The 

 l)enis consists of two ' corpora cavernosa,' il:). ir, wliich are firm 

 fil)rous Ijodies, cohering raesially and attached to the ventral surface 



of the cloaca; and of two median 

 tracts, fig. 392, 4, of a more vas- 

 cular erectile tissue, forming; the 

 walls of the mediangroove, 5, and 

 covered by a soft quasi-nracons 

 membrane. Each vascular tract 

 commences by an enlargement, 

 fig. 390, E, analogous to the bul- 

 hus iift'fhra'. The erectile tissue 

 is continued forward, thinly at 

 first, but afterwards increasing 

 in thickness, to the glans, figs. 

 391, I, and 392, which it chiefly 

 constitutes. On each side of 

 the mid-line of the penis is a 

 canal, fig. 392, /, wliich at one 

 end communicates with the 

 cavity of the peritoneum, and 

 by the other end is prolonged 

 into the substance of the glans, 

 where it terminates, blindly or 

 by a kind of reticulate sinus.' 

 The penis is provided with 

 two retractors, fig. 391, 55, 

 . .xxxvHT. fig. 392, 55', arising from the 



XX. vol. iv. p. 02, ]irep. no. 2450. 



