96 s. GOTO. 



internal and external surfaces of the penis, the connective tissue is re- 

 ])Iaced by a granular, or a uniformly staining-, homogeneous, substance. 

 In Tristoiuiim ovale I have observed in the substance of the penis 

 numerous, small, spherical, vesicular bodies ^vhich stain deeply with 

 iKPmatoxylin (PI. XXIV, fig. 1), and which are quite different from the 

 rniclei of the mesenchyma, but may be tlieir remn:)nts. In the species 

 just mentioned and in Trl^t. Jtipavaxithnim the internal surface of the 

 tidjnlar cavity of the penis is raised into numerous subconical or 

 m(3und-like elevations closely crowded together and pressed against one 

 anothci' (PI. XXIV, fig. 1) ; in T/'/.sf. foJiaceiim also there are similar 

 papilliP, but they are much smaller. These papilhp consist of a 

 coarsely gi'amda]" siibshmce which stain deeplv with lupmatoxylin. 

 Internally this grarnilai' substance passes graduallv into the fibrous 

 connective tissue. 



The penis is provided with a musculature of its own, which con- 

 sists of four sets of fibres, r/r., the internal and the external circular fibres, 

 the lon<iitti(liual, and the retractor fibres. Of these the external circular 

 fibres are by far the inost strongly developed. In Trist, ovale 

 (PI. XXTV, fig. 1) they form a layer about 10/^ in thickness just inside 

 the external membrane of the ])enis, but se])arated from it by a small 

 interval. Xext these come the longitudinal fibres whicli do not 

 form bundles, the individual fibres l)eing separated fiv^m one another 

 bv greater or less intei-vals. They are direct continuations of some 

 of the longitudinal muscular fibres of the body, and are attached at 

 the apex of the penis to its external limiting membrane. The 

 internal circular fibres are situated just inside the internal limiting 

 membrane c^f the penis, or in those cases where the internal surface of 

 the penis is raised into pa])ilkr, just at the base of these, and are, so 

 far as I have observed, arranged in a single row. The individual 

 fibres are also smtdler than the external circular fibres. The retractor 



