96 S. GOTO. 



internal and external sui'faces of the penis, the connective tissue is re- 

 placed by a granular, or a uniformly staining, homogeneous, substance. 

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

 numerous, small, spherical, vesicular bodies which stain deeply with 

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

 nuclei of the mesenchyma, but may be their remnants. In the species 

 just mentioned and in Trist. hipamsiticitni the internal surface of the 

 tubular cavity of the penis is raised into numerous subconical or 

 mound-like elevations closely crowded together and pressed against one 

 another (L'l. XXIV, fig. 1) ; in Trist. foliacewn also there are similar 

 papilla3, but they are much smaller. These papilla3 consist of a 

 coarsely granular substance which stain deeply with hajmatoxylin. 

 Internally this granular substance passes gradually into the fibrous 

 connective tissue. 



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

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

 the longitudinal, and the retractor fibres. Of these the extei'nal circular 

 fibres are by far the most strongly developed. In Trist. ovale 

 (PL XXIV, fig. 1) they form a layer about 10 fi in thickness just inside 

 the external membrane of the penis, but separated from it by a small 

 interval. Next these come the longitudinal fibres which do not 

 form bundles, the individual fibres being separated from one another 

 by greater or less intervals. 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 of the penis, or in those cases where the internal surface of 

 the penis is raised into papillas, just at the base of these, and are, so 

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

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



