i5é s. GOTO. 



wäre."'* But last «iimmer I met with two Diporpae which were 

 ah'eady producing eg'g«, but which were not united. They were 

 attached to the «ame gill very near to each other. They were quite a« 

 large as any average Dipluzuuu, and measured about 6 mm. in length 

 in a completely outstretched condition.-* They were provided with 

 four pairs of posterior suckers, but there was no trace either of the 

 ventral sucker or of the dorsal papilla. In place of the ventral sucker, 

 the longitudinal muscular layer was very strongly developed in the 

 corresponding part ; and the body shewed a sudden increase of 

 breadth just anterior to the anterior end of the ovary, looking as if 

 this part were bandaged. I have used the utmost care in detaching 

 the worms from the gill, inasmuch as I carefully scraped off the 

 gill- slime with a s[)atula, avoiding as nuich as possible any direct 

 contact with the worms. The Dq^orpae in question were observed 

 to be quite independent of each other from the moment they were 

 detached from the gill ; nor have I been able to detect any mechanical 

 injury, or the notch by wliich they might have been united to each 

 other ; so that the chance of their being detached Diphzoon is, I 

 believe, almost entirely excluded. Such a case of isolation is of 

 course exceptional ; but it shews that the Diporpa can, under certain 

 conditions, become mature without uniting with another Diporpa. 



It would have been interesting and instructive could I have 

 determined where, in this abnormal case, the vas deferens opened. 

 But unfortunately, owing to my inexperience then, I killed both the 

 Diporpae under the pressure of a cover-glass and prepared them for 

 oTobs mountinu" ; and when I afterward cut one of them into sections, 



1) Zeller— 1. c. p. 17G. 



2) The size of the common Dipori^a varies according to its stage of development. Dujardin 

 o-ives it as 0.26 — 0.56 mm. in length and 0.18 — 0.35 mm. in breadth (1. c. p. 317). A specimen 

 of the Diporpa of Dipl. parapoxum lent me by Prof. Ijiuia and possessing three pairs of suckers 

 measured about 0.6 mm. iu length. That of Dipl. nipponicum vi the same stage is of about the 

 same size. 



