74 BNTOZOA. 



Kuchenmeister states that there are no external appendages in 

 Trichocephalus comparable to those known to exist in the allied 

 Trichosomata. So far, however, from this being the case, there is, 

 in the present species at least, a remarkably prominent and more 

 or less hourglass-shaped sheath ; this projecting vulva, if it may 

 be so termed, being obliquely truncated at the free end, where it 

 is also hollowed out, or rather inverted, to give origin to the 

 centrally inclosed, vagina, whose orifice is somewhat constricted 

 (Plate v.. Fig. 6). The surface of this appendage is supplied with 

 small spines, precisely similar to those to be described in connec- 

 tion with the male intromittent organ ; the spines being likewise 

 retroverted. This observation is confirmed by the statements of 

 Mayer, who has described their occurrence at the vaginal orifice of 

 T. dispar. It also coincides with the account given by Wilson, 

 who says, " the vulva is a short and transparent papilla, measur- 

 ing 255 of an inch in length, by as much in breadth. It is 

 flattened at its extremity, somewhat larger at this point than 

 nearer the body of the animal, and curved shghtly backwards. 

 On its external surface it is studded with numberless minute 

 recurved spines, and it is traversed by the contracted canal of the 

 excretory duct of the uterus, which follows the curve of the vulva, 

 and terminates at its flattened extremity." Dr. Bberth of Wurz- 

 burg, however, in his otherwise admirable paper in Siebold and 

 Kolhker's " Zeitschrift," denies the assertions of Mayer.* Dr. 

 Bberth having discovered a series of long conical processes 

 within the vagina of T. dispar, totally unlike those described 

 by Mayer (Zeitschrift fur wissen. Zool., Band 9, s. 367), Wilson, 

 and myself, has inferred that the structures in question are 

 the same as those seen by us. I translate and quote his 

 own words : — " According to Mayer, these are similar in form 

 and size to the spines on the appendix of the penis. By 

 means of these backwardly directed points, the spicule, when 

 introduced into the vagina, is said to be retained during the 



* " Die Generationsorgane von T. dispar" Zeitschrift for April, 1860, p. 384. 



