STUDIES OX THE ECTOrAKASlTiC TKEMATODES UE JAPAN. IQ? 



name that portion of the female efferent duct that lies between the 

 ovary and the ootyp. the beginning of the latter Ijeing always distinctly 

 marked by numerous unicellular shell-glands. Its course and its 

 relation to other genital ducts are very ditferent in différent s|)ecies, 

 and will be described afterwards for each species in the systemtitic 

 pai-t, Ijut some of its common features nuist be noted down here. It 

 lies, namelv, in all the species dorsal to the uu[)aired y()lk-duct. and 

 comnuuiic:ites with it as well as with the canalis (jenih-inicslinalis when 

 such is present. In Mlcrocoli/h', A.cinc, ( hicliDColijIc. Ihclidoiiliora, and 

 Calicot ijh it bears the rcccpiacnUnn sriiiim's. In the first two g'cnera 

 just mentioned this organ is formed simply either by a lateral evagina- 

 ti(jn. or by the swelling of a portion, of the oviduct ; and seems to be 

 actually present only when it is filled with s['erm mass, and to 

 shrink together when there is no sperm to fill it. so that then it 

 seems as if entirely wanting. In Dididophoni the rcccptaculiim 

 seiiiini.s is exceedingly large, and is very c(jns])icuous. especially in 

 I)icUd. Si'ssilis (1*1. X. fig. 5). In this species it is a very large 

 sac sitiuited on the median line of the body just b;.'hind the ovar^'. 

 and consists of numerous lobes. These lobes are mostly situated 

 on the d(_>rs!d side of the body, and are separated irom each other 

 ])y a thin layer of connective tissue. They all converge towards the 

 oviduct as a centre, and comnuuiicate with it just where it makes 

 a short forward l)end to meet the unpaired yolk-dui-t (1*1. X. fig. 5 ; 

 1*1. Xt, fig. 5). In cross-section the cavities of the lobes are seen to 

 be destitute of any distinct lining membrane. In all the specimens 

 I have examined, they were always completely filled with sperm-mass. 

 In Didid. elonijdtd the seminal receptacle is also large, but is consider- 

 ably smaller than in Didid. sessilis, and is simply glol)ular in sha[)e 

 (Pi. X, fig. i)). In Didid. tctrodunis I have not observed any seminal 

 rece[)tacle, but this was, I Ijelieve, owing to the absence oï any sperm 



