330 The Whip-Worm. 



f } muscle surrounding* tlie sheath of the intromittent organ, 

 which latter is marked g ; the same letter with one dot (g) 

 marks the infundibuliform portion, whilst g indicates the ex- 

 serted part of the sheath, which is armed with the minute 

 retroverted spines ; g, shows the flask, or cup-shaped ex- 

 pansion of the free extremity of the sheath; h (fig. 2), the 

 rings formed by contraction of a portion of the sheath; i, the 

 spiculum; i (fig. 1), the infundibuliform upper end of the 

 same intromittent organ ; and i, its free pointed extremity ; 

 h, an oval mass of granules in one of the flask -shaped pouches, 

 apparently consisting of spermatic particles ; I, the cloacal 

 cavity, and m, the anus. These two illustrations have been 

 drawn with the aid of a camera from specimens prepared by 

 ourselves, and mounted for preservation in glycerine. They 

 are pretty objects under the microscope, from the graceful 

 ammonite-like spiral which the tail of the male Trichocephalus 

 invariably exhibits. When highly magnified, the free ex- 

 tremity of the spiculum is found to be scimitar- shaped, and 

 rather sharply pointed. There were no markings on its surface, 

 but we observed certain lines indicating the presence of a 

 groove or tube, such as exists in T. alispar. In regard to the 

 reproductive organs of the female, Kuchenmeister states that 

 there are no external appendages in Trichocephalus comparable 

 to those known to occur in the allied nematodes belonging to 

 the genus Trichosoma. 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 project- 

 ing from the body (fig. 6) ; it is obliquely truncated at the 

 free end, where it is also hollowed out, or rather, we should 

 say, inverted, to give origin to the centrally inclosed vagina, 

 whose orifice is somewhat constricted. The surface of this ap- 

 pendage is supplied with small spines, precisely similar to those 

 described in connection with the sheath of the intromittent 

 organ of the male, the spines being here also retroverted. These 

 observations are confirmed by the previous statements of 

 Mayer {Zeitschrift fur wissen. zool. B. 9, s. 367), but they have 

 since been disputed by Dr. Eberth, of Wurzburg (on insufficient 

 grounds we believe), in a later number of Siebold. and Kolliker's 

 Zeitschrift. We do not here propose to reconsider the contro- 

 verted points, but pass on to remark that the ova, as in other 

 nematodes previous to impregnation, are, at a certain stage, 

 flat and irregularly triangular in outline ; the thin limiting mem- 

 brane by which they are surrounded inclosing finely granular 

 contents, as seen in fig. 7. In the perfectly developed egg, 

 the external capsule, chemically composed of chitine, presents 

 the same characters as in Trichocephalus clispar ; and at either 

 pole of the ovum where the shell ends abruptly, an inner tran- 



