912 EEPORT OF COMMISSIONER OF FISH AND FISHERIES. [34] 



The penis is sometimes, not always, surrounded by a penis sheath, 

 chitinous and generally of a cylindrical form, which, more than any 

 other, seems especially adapted to strengthen the organ and direct its 

 course at copulation. The penis sheath is situated outside the penis, 

 surrounding the same, and if any connection between them exists it is 

 only through minute muscles. 



As female organ or oviduct I consider several sheaths surrounding 

 the penis sheath, and generally resembling this latter, both in form and 

 length, the width, of course, being larger. The interior of those sheaths 

 incloses always the penis sheath tightly, and resembles the same both 

 in form and size. It is sometimes chitinous, sometimes muscular, some- 

 times even entirely wanting. Both its extremities are free, neither con- 

 nected with the atrium nor with the body wall. Its interior surface is 

 never connected with the penis sheath, but both have evidently free 

 motion, one outside the other. I have called this sheath " the interior 

 sheath of the oviduct," or sometimes shortly "the interior oviduct." 

 When it is absent I have called the oviduct "single;" when present, 

 "double." 



The exterior oviduct generally consists of a large, sack-like organ, 

 surrounding the inner sheath entirely. One end of the same is always 

 attached to the body wall all around the genital porus. The interior 

 aperture is free in one respect, viz, that it is not directly connected with 

 any parts of the atrium, penis sheath, or interior oviduct. With the 

 body wall, however, it is nearly always connected by longitudinal, cir- 

 cular, or spiral muscles. This organ I consider as the true oviduct, and 

 its inner aperture, which is always to be found in the neighborhood of 

 the aperture of the inner sheaths, as the true inner aperture of the ovi- 

 duet, through which the ova enter the same, after having been freely 

 suspended in the perigastric cavity of the cingulum. 



After having entered the inner aperture I have reason to believe that 

 they pass between the inner and outer sheaths of the oviduct towards 

 the exterior genital porus. The muscles, nearly always surrounding 

 the exterior oviduct, are often so numerous that they obscure that 

 organ entirely, or at least make it very difficult to discover its inner 

 aperture. 



In the different figures appended to this paper the following abbre- 

 viations are used: p.=penis; p. s.=penis sheath; ovd.=oviduct; ex. 

 ovd.=exterior oviduct; in. ovd.=interior sheath of the oviduct; atr.= 

 atrium; eff.= efferent funnel; efld.= efferent duct; in. aptr.= interior 

 aperture; ex. aptr.= exterior aperture; pr.=prostate gland, and g. p.= 

 genital porus. As figures for reference I would suggest figures : le; 2Ji; 

 3/i; 5g; 6c; 9c; lOe; 10/; 12g; 15a; 16a, in which the different parts 

 of the copulative organs as described above are delineated. 



After this preliminary review of the copulative organs as I have un- 

 derstood them, we may return to a perusal of the same organs as they 

 have been described by ClaparMe and Vejdovsky. 



