Dorothy J. Jackson 291 



The paired vasa deferentia (Fig. 5, II, V.D.I) consist of a tube leading 

 from the testes of each side to the unpaired vas deferens formed by their 

 junction. 



The seminal tubes (Fig. 5, II, S.T.) consist of two tubes on each side 

 of the body which open into the paired vasa deferentia very close to the 

 junction of the latter with the testes. These tubes are opaque white in 

 colour and lie closely against the ventral surface of the testes. The inner 

 tube is always more or less elbowed in shape and not convoluted; the 

 outer seminal tube is very long in the mature male and greatly convoluted. 



The seminal vesicles (Fig. 5, II, S.V.) are two in number, one being 

 present on each side surrounding the paired vas deferens just below the 

 junction of the seminal tubes. It is a transparent bulb-like structure 

 consisting of eight lobes radiating from the centre. In the mature male 

 they measure 0-34 mm. by 0-17 mm. long. 



The unpaired vas deferens or common duct (Fig. 5, II, V.D. II) is 

 formed by the junction of the paired vasa deferentia a short distance 

 below the seminal vesicle. It is a long tube though when not extended 

 during copulation it is coiled in a very short space. It opens posteriorly 

 into the internal sac 1 (Fig. 5, II, I.S.), a membranous structure, the 

 anterior part of which is covered with minute scales of chitin. At the 

 junction of the vas deferens with the internal sac there is a chitinous 

 structure known as the transfer apparatus (Fig. 5, II and IV, T.A.). In 

 repose the internal sac is partially withdrawn inside the median lobe, its 

 anterior end projecting between the struts of the median lobe, but when 



I. Reproductive organs of immature female of Sitones lineatus L. from one to five 



months old x 37£, ventral view 



II. Reproductive organs of immature male, ventral view, from one to five months old 



x37|. 

 II A. Same but x 19J-. 



III. Reproductive organs of mature male eight months old as dissected in April x 19^. 



IV. Male genitalia, dorsal view x 37} . 



V. Same, lateral view. 



VI. Spiculum gastrale of male x 37|. 



A.G. = accessory gland; B.C. =Bursa copulatrix; I.S. = internal sac; M=median lobe; 

 M.S. =struts of median lobe; M.U. =muscle; 0=paired oviduct; R=receptaculum 

 seminis; S.P. =spiculum ventrale; S.T. =seminal tubes; S V. =seminal vesicle; T = testes; 

 T.A. -transfer apparatus; T.C. =terminal chamber; T.F. =terminal filament; T.G. = 

 tegmen; T.S. =tegminal strut; U uterus: V.I). I=paired vasa deferentia; V.D. II=vas 

 deferens. 



1 The terminology of the genitalia which 1 here use is that adopted by Dr David 

 Sharp, in his most valuable and helpful paper. "Studies in Rhynchophora," Trans, of the 

 Ent. Sor. of London, Dec 1918, pp. 209 222. 



