ON A PRORHYNCHID TURBELLARIAN. 643 



vesicles situated close to the sides of the intestine. The 

 vitello-ovary consists in its posterior portion of indifferent 

 reproductive cells ; further forwards it contains a row of ova 

 surrounded by yolk-cells. 



Impregnation. — Embedded in the parenchyma^ close to the 

 ovary, not far from its posterior end in the specimen, without a 

 bursa seminalis, is a chitinous tube, which is without doubt the 

 remains of the chitinous part of the penis of another individual. 

 This circumstance affords very strong evidence in favour of 

 the conclusion that the sperms of one individual are conveyed 

 into the interior of the ovary of another, to form the seminal 

 bursa by the penis piercing the body-wall and penetrating to 

 the ovary. The structure of tlie penis and vesicula serainalis 

 would of itself suggest such a mode of copulation ; the whole 

 apparatus has exactly the form of a hypodermic syringe, with 

 a compressible ball instead of a cylinder and piston. 



A mode of copulation in which a wound is inflicted in any 

 part of the body by the penis, and masses of sperms are dis- 

 charged into the wound, was long ago described by Lang^ as 

 occurring in many Polycladida. But, so far as I am aware, 

 this is the first recorded instance of the direct injection of the 

 ovary with sperms through a perforation of the body-wall by 

 means of the penis. 



In the incomplete condition of our knowledge of the genus 

 Prorhynchus it is somewhat difficult to give a diagnosis 

 which will clearly define the new form. Von Graff's definition 

 of Prorhynchus is as follows: — " Prorhynchida mit Wim- 

 pergriibchen, Mund am Vorderende des Korpers, ein chitinoses 

 copulationsorgan vorhanden, Korper fadenformig gestreckt.'^^ 

 In all of these points, with the exception of the last, which is 

 not important, the new form agrees with Prorhynchus. But 

 it differs from it apparently in several material points not 

 included in v. Graff's diagnosis. Such are the more complex 



1 "Der Bau von Gunda segmentata, &c.," ' Mittb. ans der Zool. Stat, 

 zu Neapei; Bd. iii, p. 222 (1882); 'Die Polycladeu,' pp. 231 and 636 

 (1884). 



= Loc. cit., p. 263. 



