150 S. GOTO. 



taneous displacement of the latter from the base of the penis 

 towards its top; so that the cavity of the penis is mo'rphologic- 

 ally speaking as much the external surface of the body as 

 the genital atrium, and the prostate glands are therefore to be 

 regarded as a special modification of the dermal glands, — a view, 

 clearly in accordance with some facts observed in Temnocephala.^'' 

 The tissue of the large papilla projecting into the genital atrium 

 at the top of which the vas deferens opens in Hcxacotijle is not 

 bounded off from the surrounding mesenchymal but that it is 

 the homologue of the penis will, I believe, scarcely be contested 

 by any one. In Monocotijle (PI. XVIII, fig, 3),, on the other 

 hand, the connective tissue that forms the substance of the penis 

 has undergone some transformation, having become fibrous with 

 the fibres arranged at right angles to the internal and ex- 

 ternal limiting membranes of the penis. It is, however, not yet 

 distinctly (separated from the surrounding mesenchyma by a mem- 

 brane. The penis encloses, in this genus, a tubular, chitinous 

 organ — the chitinoas penis — which is attached to it at the bottom of 

 its cavity, and into which the vas deferens opens. This chitinous 

 penis Is regarded by St.-Remy'^ as the transformed terminal portion 

 of the vas deferens. It seems to me, however, to be more in accordance 

 with facts to regard it as the prolonged portion of the inner limiting 

 membrane of the penis, which has then undergone a chitinous trans- 

 formation ; and as this limiting membrane is morphologically no 

 other than a portion of the lining membrane of the genital atrium, 

 which is again but the invaginated portion of the investing 

 membrane of the body, the chitinous penis is, in my opinion, to 



]). Haswell— On Temnocephala, an Aberrant Mouogenetic Trematode. Quart. Joum. of 

 Mic. S3., vol. 28, 18S8. p. 288. 



2). 8t.-Eemy— /. e. p. 2-1. 



